St. Joseph Cathedral is a church on Nha Tho Street in the Hoàn Kiếm district of Hanoi, Vietnam. It is a late 19th century neo-Gothic style church that serves as the cathedral of the Catholic Archdiocese of Hanoi to nearly 4 million Catholics in the country. Construction began in 1886, with the architectural style described as similar to Notre Dame de Paris. The church was one of the first structures built by the French colonial government in Indochina.