The Hyattsville Post Office was not the only fallout shelter in Prince George’s County.

According to a Nov. 2, 1961, article in the Washington Post, the Prince George’s Plaza shopping center, which opened in 1959, “authorized the use of 260,000 square feet of auditorium, tunnel and basement space” for a fallout shelter.

The facility was estimated to accommodate 3,600 people, making it probably one of the largest in the county.

(In the same article, an official with the U.S. Civil Defense agency estimated that, with minor modifications, Union Station could be designated a fallout shelter for at least 5,000 people.)

Another Washington Post article from May 14, 1963, showed the lengths people went to during the fallout shelter mania of the early 1960s.

It noted that a group of 33 research reserve officers were locked without warning in an underground fallout shelter beneath the naval medical center in Bethesda as part of a test to “see how they will fare … on a diet of biscuits and soup” as well as psychologically.

The group thought they were in town for a two-week seminar on fallout shelter design. “They next thing they knew they were shut up in a shelter of corrugated steel under five feet of earth,” noted the Post. Their only amenity was “a supply of chewing gum.”

And then there’s this: “To increase the realism of the test, a radioactive pellet will be lowered into a tube outside the shelter. The men will soon learn they can leave the shelter when the radioactivity has dropped to a safe level.”

One of the test subjects was Lt. Cmdr. Clyde R. Richards of West Hyattsville.