Sirius & Theo: 10:50PM, By the Fireplace.
Sirius barked with laughter; it was an answer not unlike one he himself may have given, and he always appreciated it when people thought as he did. "You'd like old Joe, then. It's this freestanding clocktower in muggle Birmingham, 100 metres high. Tallest in the world. One of my mates lived near it — we flew up there once to have a drink, and charm the clock face Gryffindor colours."