In 1942 Op-20G expanded into seventeen subsections and its chief became as Assistant Director for Communication Intelligence in the Office of Naval Communications. This coincided with the inclusion of all COMINT functions, including direction finding.
On February 7, 1943, Op-20G moved from the Army-Navy Building on Constitution Ave. to the new Communication Supplementary Annex, 3801 Nebraska Ave., Washington D.C. This location was later renamed Naval Communication Station Washington, D.C. and in September 1950 it became the Naval Security Station.
In 1996, Naval Security Group Headquarters moved from Nebraska Ave to Ft Meade. On January 27, 2003, the Department of Homeland Security headquarters moved Into 3801 Nebraska Ave.
History of the Nebraska Avenue Complex (NAC)
1917-1942 – Mount Vernon Seminary
Elizabeth J. Somers (The George Washington Library) The Nebraska Avenue Complex sits on a tract of land formerly known as Grassland. Grassland was the country home of Nathan Loughborough, Comptroller of the Treasury under President John Adams. Loughborough is said to be the first resident of the District of Columbia to refuse to pay property taxes under the principle of taxation without representation. Other owners include William Whitney, Secretary of the Navy under Grover Cleveland, and Robert E. Lee, Jr., son of the famous Civil War general.

In 1875, Elizabeth J. Somers founded the Mount Vernon Seminary for girls on F Street. In 1910, Somers expanded with the purchase of 15 acres of land along Nebraska Avenue. New York architect Wesley Sherwood Bessell designed the original buildings on campus that opened on October 3, 1917. Mrs. Somers’s successor, Mrs. Adelia Gates Hensley, continued the expansion and built headmistress residence Gatesly, the chapel, a field house, and gymnasium. By 1928, the school had grown to nine buildings and over 38 acres of land.
The Nebraska Avenue Complex sits on one of the highest points in Washington D.C. In 1929, work had begun on the Field House (Building 14) and the Gymnasium (Building 12). (Mount Vernon Seminary and College Archives, The George Washington University Library)

The Elizabeth J. Somers Memorial Chapel, designed by Wesley Sherwood Bessell, was constructed in 1925 as a memorial to the seminary’s founding mistress. Contrary to popular myth, the chapel never had a steeple. There is no relationship between the chapel and the steeple located at the intersection of Nebraska Avenue and Van Ness Street. (Library of Congress)

Mount Vernon students (circa 1930s) enjoyed spending their free time at the Field House at the base of the hill. This building is now the NAC cafeteria. (Mount Vernon Seminary and College Archives, The George Washington University Library)

Almost 100 years later, elements of the main building, once called the Refectory, remain on the campus. The seminary’s motto, Vincit Que se Vincit (she conquers who conquers herself) is fixed in a stone over the center entrance way. The main staircase still exists and now has a rope banister installed by the Navy. Unfortunately, the swimming pool on the lower level no longer exists. (Library of Congress)
1942-2009 – Naval Communications
Mount Vernon students left for winter break in December 1942 and never returned to the Nebraska Avenue campus. The Mount Vernon Seminary campus was pressed into military service for the Navy’s efforts to decrypt German communications. Unlike the Navy Department’s building on Constitution Avenue, the campus fit the Navy’s requirements; it was located away from tall buildings; settled on high ground with clear sight lines to the Pentagon, Fort Meade and other military installations; and contained a group of buildings, including a dormitory, that could be immediately converted for Navy use.
The federal government formally acquired the land for $1.1 million on July 20, 1943. The Mount Vernon Seminary first moved north on Massachusetts Avenue to Spring Valley and then south to Foxhall Road where it is now the Mount Vernon Campus of George Washington University.
The newly named Naval Communications Annex became the center for many secret intelligence activities. One of the most important projects was the breaking the German Enigma cipher system. Banks of cryptanalysis machines, known as bombes, operated around the clock at the facility deciphering German code.), Members of the Women’s Reserve of the United States Naval Reserve, known as WAVES (Women Accepted for Voluntary Emergency Service), operated most of the machines.
WAVE operates a code breaking machine known as a bombe at the Naval Communications Annex. The bombes were built in secrecy by WAVES at the National Cash Register Company in Dayton Ohio and shipped to Washington. Each 5,000 pound bombe stood seven feet high, ten feet long, and two feet deep. (National Security Agency)
In February 1944, nearly 3,000 WAVES were stationed at the Naval Communications Annex. WAVES were sworn to secrecy and told that discussion of their work outside of approved channels could mean facing the death penalty for treason. Inside the bombe decks, WAVES worked long hot hours and never knew how their individual work fit into the cryptanalysis process.
After a WAVE completed a run on her bombe (which took 20 minutes) she gave her print out to her supervisor for verification. The supervisor then took the results to the Watch Office for logging. The verified and logged results were sent via a pneumatic tube system to the cryptanalysts located in Building 2. (National Archives and Records Administration)
Due in part to the efforts of the personnel at the Naval Communications Annex, the Allies broke the German Enigma code in 1944. By May of that year, the German submarine fleet was crippled as Allied intelligence was able to decipher their communication.
Although most joint military intelligence efforts eventually relocated to Ft. Meade, Maryland, with the creation of the National Security Agency (NSA) in 1952, some elements remained at the location renamed to the Naval Security Station (NAVSECSTA). Intelligence operations continued to move to Ft. Meade between 1968 and 1995. In 1998, NAVSECSTA was renamed the Nebraska Avenue Complex (NAC).
1944 Photo photo taken of Naval Men stationed at the Naval Communications Annex in front of Artemas Ward Memorial at Ward Circle, Nebraska and Massachusetts Avenues. (Robert H. Davis)
U.S. Naval Security Station (NAVSECSTA). The ”street” names at the campus intersections reflect history including Grassland Place, Somers Court, Seminary Drive, Intelligence Way, Cryptologic Court, and Enigma Way. Wenger Street is named for Rear Admiral Joseph N. Wenger, a pioneer in the development of machines for use in cryptanalysis and later a leader in the centralization of the Navy Communications Intelligence. (National Security Agency)
2003 – Securing the Homeland
The Department of Homeland Security (DHS) began officially operating at the NAC on January 27, 2003. DHS selected the NAC because the large campus could accommodate a headquarters operation and the department would not need an exemption from the statutory requirement that main government agency offices be located in the District of Columbia. The Navy vacated the Nebraska Avenue Complex in 2005.
On September 12, 2002, President George W. Bush and Tom Ridge, Director of the Office of Homeland Security (OHS), toured the Nebraska Avenue Complex, future home of the Department of Homeland Security. (White House photo, Eric Draper)
During DHS’s early years at the NAC, the Building 7 and Building 88 Visitor Centers and the Vehicle Screening Building were added. The perimeter security fence, with guard booths at several entry points, was constructed to provide Level 5 security.
An exhibit of artifacts related to the founding of Homeland Security was installed in the NAC 1 lobby in 2013 to commemorate the 10th Anniversary of DHS’s move to the NAC. (DHS Photo)
In the future, many of the headquarters offices currently located at the NAC will move to the St. Elizabeth’s Campus located in southeast Washington D.C., which will become the new Homeland Security Headquarters. The NAC will continue to be a DHS occupied facility and will begin a new chapter.
President Barack Obama visited the NAC on February 2, 2015, to announce the FY 2016 Budget Request. Accompanied by Secretary Jeh Johnson, President Obama walked along Seminary Way to Building 12, the Gymnasium, where the event was held. (DHS Photo, Jetta Disco)

Source: dhs.gov
7 February 2017 at 14:43
Good article. I was stationed there from ’83 to ’86 and thought the building and the surrounding area were beautiful. Appreciate the history lesson.
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8 February 2017 at 10:22
This is an excellent piece of work. Take my hat off to the author(s)
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8 February 2017 at 14:27
I was stationed there in 62-64 at the communications center located in the basement or former swimming pool area? Thanks for the great history lesson of this facility stirring old memories.
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10 February 2017 at 00:21
What? No mention of the WW II efforts to break Japanese code? My mother, now 94, was one of the WAVES who worked on that project.
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10 February 2017 at 19:21
Thank for stopping by StationHYPO and for your comment.
We are very aware of the significant contributions WAVE made during World War II. In fact, we did a three part series on NSG WAVES in July 2016. Please let me direct to part 1 of 3 in the series in the link below.
https://stationhypo.com/2016/07/19/nsg-waves-during-wwii-1-of-3/
If you provide a well written account of your Mother’s service while at 3801 Nebraska Ave, we would be happy to post it.
Sincerely,
StationHYPO
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9 March 2017 at 19:13
I am researching the Nebraska Avenue Complex for historical data. If you are interested in sharing your story, please email me at joyce.conyers@navy.mil? Information must be supported by official verification.
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25 June 2018 at 17:32
i love this research
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18 February 2019 at 22:45
Loved the walk through history, and so many great memories. Was station at 3801 62-64, 74-77, 80-83. Met many people there whom I still consider good and present friends. My detailers loved me, strictly because I was one of the few who did not mind being staton in Washington, and as a matter of fact on all my station rotations, I requested Washington, and needless to say I got it. Nobody wants Washington.
CTACM John E. Booker, Ret
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4 February 2020 at 09:25
John: Double check your records pertaining to your “80-83” comment. I got there in 84 and you were there shipmate.
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31 March 2019 at 14:23
I was stationed there from Jan thru Dec, 1969 (50 years ago this year). I was waiting for “C” school, so during that year I worked mostly on teletype machines My year there and the arrival of a new piece of teletype test gear, helped me pass the CTM E5 exam in Feb ’70. And yep, the communication room was built above the swimming pool. I was shown a closet door in which, using a flashlight, you could look down thru a crack and see the pool’s tile floor. If you jumped up and down hard enough you could make the floor bounce. The pool fill wasn’t very strong. Most of us single guys lived at the tri-service barracks in Ft. Myers (Army run). We tended to eat at McDonalds a lot, since the Army food sucked.
In the small world department, one of the chiefs that I worked with ended up being my chief at Adak, where I went after “C” school.
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12 May 2019 at 15:34
Mike: I only have fond memories of Ft. Myers Army food. Especially before going on a mid watch, you could really chow down at night. I remember eating fried eggs and bacon along with fried chicken and biscuits – the day’s leftovers. After six months living on base, I made CTO4 and moved into an apartment. The Army knew much more about cooking than did I…
I also remember the EM club at Ft. Myers, the cheap beer and great chili hot dogs. After I bought a car, I found the Navy club Jason, and that became my spot.
After 50 years, I probably forgot all the bad stuff and only remember the good!
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12 May 2019 at 14:50
I was an O-Brancher at 3801 Nebraska Ave 1967-1969. Best duty station ever! Went to USNS Mueller, then to Rota where I was discharged in 1971. Then, I made a 40-year career in electronics/computers/networking because of my navy training and experiences. I would gladly do it all over again!
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12 May 2019 at 14:56
I was an O-Brancher at 3801 Nebraska Ave 1967-1969. Best duty station ever! Went to USNS Mueller, then to Rota where I was discharged in 1971. Then, I made a 40-year career in electronics/computers/networking because of my navy training and experiences. I would gladly do it all over again! Mike Brown and I may have crossed paths, but I don’t remember. The Mat room was upstairs by GENSER. Maybe Mike knew my pal Denny Allen, a CTM5 stationed there also in ’69.
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21 August 2019 at 13:10
Great info. I was a CTA There 67-69. Worked in N63 down in the Crypto Equipment and Publications Vaults. Interesting times but DC did have some great places to hang out. Vaults were also ARFCOS )Armed Forces Courier Station (Washington Navy) in 60’s.
J. Lombard CTA3
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3 February 2020 at 22:28
Arrived at SecSta in July 1965. Time erases my section assignments but maybe G50 and G12 which ring bells. I volunteered to be a Fire Marshall at the station for about six months as it got me out of the fire traps at the old Quarters K in Arlington. This was great duty as we ate with the Marines (great food) and I had a reserved parking space. Duty in DC was good for a single third class A branch CT and I ended up renting an apartment with another sailor a few blocks away. I got out in June 1967 and ended up on the Montgomery County Police Dept which was Home to many former CT’s and Marines from SecSta. Thanks for the great history lesson and good memories in my 75th year.
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15 October 2020 at 02:25
I was station with Marine Barracks 1973-1975 was great duty station
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10 November 2020 at 22:21
NavSecSta 1989-1991 Public Works/Transportation. I lived in barracks on base for 16 months. Wondering if anyone knows Senior Chief Nottingham. I would love to thank him for watching out for me. 🙂
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21 December 2020 at 17:08
I was a CTA stationed here from 1970 – 1972 providing administrative support to the Commanding Officer, James Pearson. Also worked for Robert Maze, Administrative Officer and Robert Klein, Administrative Chief all wonderful individuals. Was an amazing experience!
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12 November 2021 at 01:41
I was stationed there for 18 months starting in fall of 1952 to spring of 1954,was a Marine guard great duty station,Eugene Summers
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12 November 2021 at 04:08
Thank you for your time and service – is too spent time there 1967-1969
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23 February 2022 at 00:19
I was station there 1972 – 1973 I was Navy all the way in charge of the electronic store room.
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25 February 2022 at 02:16
Was that the “Store Rooom in the basement of the Building on the the Right rear of the Station? If so in 1966-1969 it was Division N63 vault of both Publications and all Electronic gear – RTTy-TTTy- Etc.
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2 February 2023 at 13:55
I was stationed at NSS Washington for 3 tours from 1960 thru 1968, loved it. Carried the mail to offices 1960 thru 1962. Also worked in G61 and G62.
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2 February 2023 at 16:37
From CTO3 Richard J. Roush, SPO operator, and everything else in the comm center…
I was an O-brancher at 3801 Nebraska Ave from late 67′ to early 69′. We stood day-mid-eve watches during that time. That was the greatest schedule because the bars were still open after that last watch! We were a tight knit group of guys, the best of friends. We loved to party, but while on the job, we were all business. All experts in keeping the crypto circuits in sync, quality control, proper routing, and SPO ops. Like most, I could type code groups or garbled intercept messages at 100 wpm, and read the holes in that pink punch tape from across the room. From DC to the USNS Mueller, to Rota, the navy trained me to be the best that I could be. This carried on for the next 45 years in civilian life as a professional engineer.
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