Civic Center is San Francisco at its most monumental and its most honest at once: a Beaux-Arts plaza built to declare the city's recovery from 1906, set hard against the Tenderloin, the neighbourhood the grand plan never reached. Walk both; the contrast is the point.
Start in United Nations Plaza, named for the charter signed nearby in 1945, and read it as it is before you turn west to City Hall. The dome is taller than the US Capitol's, raised deliberately to say the city had come back; the rotunda inside is free on weekdays, so look up the grand stair. The Asian Art Museum sits in the old library on one side, the new main library on the other — step into the atrium, free, for the skylit drop the full height of the building.
Then cut into the Tenderloin, to the Tenderloin National Forest on Cohen Place, an alley turned community garden and mural yard where the neighbourhood tells its own story. This is a lived-in block; tread lightly. End by walking east to Powell, the grit shading into the shopping streets within two blocks, and the trains underneath.