Cha-ching! The nation's paper currency is designed and printed here. Guides lead 40-minute tours during which you peer down onto the work floor where millions of dollars roll off the presses and get cut (by guillotine!). It's actually a pretty dry jaunt; don't expect exciting visuals or snappy dialogue. In peak season (March to August), timed entry tickets are required. Get in line early at the ticket kiosk. It opens at 8am. Tickets are often gone by 10am.
During non-peak season (September through February), no tickets are required and you can come in through the main entrance at 14th and C Sts; tours take place every 15 minutes from 9am to 10:45am and from 12:30pm to 2pm.
The building is expected to undergo structural renovations starting in late 2018; tours will continue to run, but there may be tweaks to the scheduled times, so call or check the website before heading out.