Pentagon Travel Guide

Across the Potomac along I-395. Closest Metro stop is Pentagon. Mon-Fri 9.30am-5pm, last tour 3.30pm. Admission free. tel 703/695-1776,

The headquarters of the US military establishment is one of the world's largest chunks of architecture: though it's only five stories tall, the total floor area - 6.5 million square feet - is three times that of the Empire State Building. Each of the five sides is more than 900ft long, and the combined length of all the internal corridors exceeds seventeen miles. These and other useless factoids are about all you get from visiting the behemoth building, apart from the opportunity to see at firsthand the people responsible for thwarting the country's adversaries. In the one novel departure from the norm, the service-personnel guides who accompany you walk backward the entire time to ensure that foreign agents posing as gawking tourists don't slip off into the restrooms.

Ninety-minute guided tours used to leave every thirty minutes from the small waiting area inside the entrance. Nowadays, you should call ahead to check on the status of tourist visits. Tours were suspended indefinitely after September 11, 2001, when terrorists crashed a hijacked airplane into the Pentagon, killing nearly two hundred people and destroying a sizable section of the building.