It takes a little stagecraft to bring these ruins to life, but it's amazing what low lighting and Latin chanting can do. This Roman temple was dedicated to the all-male cult of Mithras, a little-understood religion; what you see today is a sympathetic reconstruction of the temple after it was uprooted in the 1950s for display up the road. A well-presented display case near the entrance shows intriguing fragments of Roman life in London.
For guaranteed timed entry, book online in advance. All floors have step-free access.