The Largest Cathedral in the World

     Ironically the largest church in the world is located in the smallest country in the world as St. Peter's Basilica is in Vatican City which is considered its own country. St. Peter's Basilica is a magnificent structure built from 1506-1626 by a number of different architects including Michelangelo who designed the dome. St. Peter's is a Roman Catholic church and can hold some 60,000 people. It is certainly one of the most famous buildings in the world and one of the most visited by tourists and worshipers. Basilica of the National Shrine of Our Lady of Aparecida in Brazil - 129,000 square feet 

I personally think this one is much prettier and boasts more masterfulness.

Milan Cathedral in Italy - 91,000 square feet

I got this information at http://united-states-canada.knoji.com