The Basílica del Santísimo Sacramento is Colonia's main church, occupying a prominent corner of the historic quarter facing the Plaza Mayor. The current building dates from the early 20th century — the original colonial church was destroyed in one of the many sieges of the town — but the site has been a place of worship since the Portuguese founding of the settlement in 1680.
The church is a straightforward but handsome example of colonial revival architecture, with cream-coloured walls and a modest bell tower that appears in most photographs of the Barrio Histórico's rooflines. The interior is clean and simply decorated; services are still held regularly, giving the building a working life that many colonial churches in tourist areas have lost.
The plaza in front, the Plaza Mayor, is the heart of the Barrio Histórico and the most logical base for exploring the quarter. The small museums of the Barrio — the Municipal Museum, the Portuguese Museum, the Tile Museum — are arranged around the plaza and its immediate surroundings.