Take Massachusetts Avenue and stay to the north of the Mt. Vernon Square Library. Turn right on 7th Street NW and immediately left on K Street. Continue on K to 1st Street NE. Turn right on to 1st Street NE and continue to the APA building.
Come into the city on New York Avenue and turn left on to North Capital Street. Turn left on to L Street NE and right on 1st Street NE to the APA building. (Note: there is no left turn on to K Street from North Capital Street during rush hour).
Take the Suitland Parkway or 295 to the South Capitol Street bridge. Follow South Capitol Street to 395 north, which will lead you into the tunnel which runs underneath the Mall. Follow signs to Massachusetts Avenue, and you will come out of the tunnel on to 2nd Street NW. One option is to continue north on 2nd Street NW to right on K Street and right on 1st Street NE. Another option is to take 2nd Street NW to right on Massachusetts, left on North Capitol and right on G Street (or G Place), and left on 1st Street NE to the APA building.
There are two good options:
Take Route 50 to Constitution Avenue. Cross Pennsylvania Avenue and continue on Constitution to left on Louisiana Avenue NW. Continue on Louisiana to left on North Capitol Street, then right on to G Street NE, and left on 1st Street NE to the APA building.
Take 395 North (Shirley Highway), across the 14th Street Bridge to the Southwest Expressway. Watch for signs to 395 North, which will take you to the tunnel going under the Mall. Take the exit that reads Massachusetts Avenue, which will lead you to 2nd Street NW. You may continue on 2nd Street NW to right on K Street and right on 1st Street NE, or you may turn right on Massachusetts, left on North Capitol Street, right on G Street and finally left on 1st Street NE to the APA building.