Hanoi is famous for its churches so if you are in the city, you must definitely visit the St. Joseph's Cathedral. There is also a lake nearby which you can choose to visit.
Location: Na tho street, Hanoi. The church is right on the road and you wouldn't have any difficulties in finding it, the place is quite accessible.
History: The church was one of the first structures built by the French colonial government in Indochina and it was opened in the year 1886.
Highlights: The church serves as the Roman Catholic Archdiocese to almost 4 million people in the country. The church conducts mass several times in a day so you can be a part of it if you are there at the right time.
Best time to visit: Every Sunday, they organize a mass at sharp 6 in the evening, so this will be the best time for you to visit the church.