The Nob Hill Masonic Center is a large Masonic complex beside Grace Cathedral, used for concerts, ceremonies, and lodge functions. Its stern mid-century facade is easy to notice on California Street, especially when you are walking the hill between the cathedral and the cable car line.
The visitor interest is mostly architectural and historical, with a small museum of Freemasonry inside. It is a selective stop, but it fits well into a Nob Hill walk.