01 Prague Castle
Entry from €30, and the confusing part is that the grounds are free and the buildings are not: the standard circuit covers St Vitus, the Old Royal Palace, St George's and Golden Lane. Go up in the late afternoon when the coach groups have gone and the cathedral light is worth the climb. The changing of the guard at noon is the busiest hour of the day.
02 Astronomical Clock & Old Town Square
The clock face costs nothing to watch and the tower above it is ticketed from €30. The hourly show is ninety seconds long and mildly disappointing, which everyone tells you and everyone still watches; the tower view over the square is the part that justifies a ticket.
03 The Jewish Quarter
A single ticket covers the synagogues and the old cemetery, and this is the one place in Prague where a guide changes the visit rather than decorating it — the Pinkas Synagogue walls and the cemetery need the context. Closed on Saturdays and Jewish holidays.