What is the unusual characteristic of the Cathedral Zipaquira?

The Salt Cathedral of Zipaquirá (Spanish: Catedral de Sal de Zipaquirá) is an old underground Roman Catholic church built within the tunnels of a salt mine 200 metres (660 ft) underground in a halite mountain near the city of Zipaquirá, in Cundinamarca, Colombia.

It is a tourist destination and place of pilgrimage in the country. The temple at the bottom has three sections, representing the birth, life, and death of Jesus. The icons, ornaments and architectural details are hand carved in the halite. Some marble sculptures are included. The cathedral also is considered one of the world's most notable achievements.

A Colombian prized architecture, being described as a "Jewel of Modern Architecture".

The complex is located in Zipaquirá, in Cundinamarca Department, 49 kilometres (30 mi) north of Bogota, at 2,652 metres (8,701). The cathedral is a functioning church that receives as many as 3,000 visitors on Sundays, but it has no bishop and therefore no official status as a cathedral in Catholicism.

Salt deposits in Zipaquirá formed around 250 million years ago, and were raised above sea level during the late Tertiary period.

The Salt Cathedral which was inaugurated on August 15, 1954, and dedicated to Our Lady of the Rosary, Patron saint of miners.

The construction cost of the original church was over 285 million U.S. dollars. The building had 120 m length, 5.500 m² surface and 22 m height. It had six main columns, and a maximum capacity of 8,000 people.