Standing at 33 Thomas Street in the Civic Center neighborhood of New York City is a 550-foot tall monolithic, granite-clad, concrete building. Even in a city like New York, where tall buildings are typical, people passing by would look up to gaze at this intimidating structure —their attention drawn not by the building’s height but by its fortress-like appearance. Aside from a couple of ventilation openings on the sides, the building’s bare concrete slab façade is without a single window.

The Long Lines Building is owned by the multinational telecom company AT&T, and is indeed an impenetrable fortress. When it was built in 1974, AT&T asked architect John Carl Warnecke to design a structure that could withstand a nuclear blast and protect its occupants from fallout for up to two weeks after the attack. Such concerns were not uncommon at that time, and AT&T wanted to be sure that their expensive equipment stayed undamaged.

Photo credit: Wally Gobetz/Flickr