Unlike most other Nike-era Army Air Defense Command Posts which were collocated with U.S. Air Force long-range radar sites, the U.S. Army direction center at Fort MacArthur was separate from the radar equipment at San Pedro Hill AFS. Instead, the Army emplaced the Los Angeles Defense Area's AN/FSG-1 'Missile Master' (later AN/TSQ-51 'Missile Mentor') on Fort MacArthur's Lower Reservation, east of Pacific Avenue between between 33rd and 34th Streets.
Below are a couple of photos dated 1972 which show the Army's blockhouse when it was still in use (it's the large square building with the dark roof). This direction center inactivated in 1974 as part of the Army Air Defense Command's phase-out of the Nike missile system in the continental United States. In fact, the Army Air Defense Command phased out almost all its Nike missile air-defense system in the U.S. in 1974, leaving only a few 'Hercules' batteries in Alaska under U.S. Army Alaska and a few 'Hercules' and 'Hawk' batteries in South Florida under the U.S. Army Forces Command.
Today, the Fort MacArthur 'Missile Master'/'Missile Mentor' blockhouse is no longer extant. The Air Force demolished the structure during the 1980s to free up room for housing and support facilities for Los Angeles AFS (now Los Angeles AFB).
-- Tom Page and Mark Morgan
The following three photos source: http://www.californiacoastline.org/
This 1979 photo shows the Nike Missile-Master building while it was still standing; it would be torn down only 5 or 6 years later.
The three vintage photos below came from the 'California Coastline' web site, 1972 collection.
Since the Army's old Nike Missile-Master / Missile-Mentor building (LA-45DC) is long gone, the images above shows exactly where it was once located, and what that site looks like today.
Remaining about the same today are the bluffs and the shoreline to its south; the tennis courts; the main streets; the house at the NE corner of Pacific Ave. and 34th St. plus its detached garage; and the house plus its detached garage on the north side of Pacific Ave. due north of 33rd St. These landmarks all serve to identify the old Nike Missile-Master / Missile-Mentor building's site precisely.
Note: The image on the left is from the ''California Coastline'' 1979 collection, and the image of the right is from the Microsoft Vitual Earth ''Bird's Eye'' 2007 collection. Both are looking almost due north.