Where: James A. Farley Post Office, 8th Avenue and 33rd Street

When: The lobby is open 24 hours a day, seven days a week, including holidays

What: Pick up a copy of the self-guided tour booklet at Window #45, then explore this wonderful 1914 building, designed by McKim, Mead & White as a sister building to the late Pennsylvania Station across the street. If you're not sure what follows the words "Neither snow, nor rain..." or if you've ever wondered where letters to Santa are collected, this is the place to find out.