Iglesia grande de Andacollo, Byzantine church in Andacollo, Chile.

The Iglesia grande de Andacollo, also called the Basílica Nuestra Señora del Rosario, is a neo-Byzantine church designed by Italian architect Eusebio Chelli and built from 1873 to 1893. Its red twin-tower facade has five entrances, and the towers rise 53 meters. The five-aisled cross-shaped interior is supported by 36 columns, with a dome 45 meters high over the crossing; the walls are adobe covered outside with galvanized iron sheets and inside with Guayaquil cane.

The parish church of 1660 became too small for the growing devotion, so Bishop José Manuel Orrego Pizarro decided in 1869 to build a larger church on land of the Nuestra Señora del Rosario brotherhood. Work ran from 1873 to 1893, with local residents making the adobe bricks; delays came from hauling materials into the mountain town. 8,000 believers attended the consecration, and in 1998 John Paul II gave the church the rank of minor basilica.

The image venerated here is a Virgin of the Rosary carved in Lima and brought to Andacollo in early 1676, after the original image was lost; it was canonically crowned at Christmas 1901 with the approval of Pope Leo XIII. Dances offered to the Virgin began around five years after the first chapel of 1580. The Fiesta Chica falls on the first Sunday of October, and the Fiesta Grande on 24, 25 and 26 December.

The church stands on a forecourt that can hold up to 10,000 visitors during the December festival. The main altar came from Paris, and the interior is lit by large glass windows and the crossing dome. Crowds peak on 24, 25 and 26 December for the Fiesta Grande and on the first Sunday of October for the Fiesta Chica.

The 53-metre twin towers rise in four tapering storeys, and the walls are adobe faced outside with galvanised iron sheets and lined inside with Guayaquil cane. Local residents made the adobe bricks, and delays came from hauling materials up to the mountain town. The main altar was made in Paris.