Hanoi's neo-Gothic St Joseph Cathedral was inaugurated in 1886, and has a soaring facade that faces a little plaza that's usually stuffed with selfie sticks and posses of preening photographers. The church's most noteworthy features are the looming twin bell towers, elaborate altar and fine stained-glass windows. Entrance via the main gate is only permitted during Mass: times are listed on a sign on the gates to the left of the cathedral.
At other times, enter via the Diocese of Hanoi compound, a block away at 40 P Nha Chung. When you reach the side door to the cathedral, to your right, ring the small bell high up on the right-hand side of the door.