Hanoi's neo-Gothic St Joseph Cathedral was inaugurated in 1886, and boasts a soaring facade that faces a little plaza. Its most noteworthy features are its 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.