Cathedral of St. Olav, sometimes called "Nidaros Cathedral", was under construction for a century – 1140 years before the beginning of the XIV century. Despite numerous fires and rebuilding, this is one of the most beautiful medieval cathedrals in Europe. Buried in the Cathedral of the Norwegian kings, including St. Olaf, on the worship of relics which pilgrims flocked from all over Europe.

The facade of the magnificent Gothic Cathedral is decorated with reliefs and statues of kings and saints. The interior is a maze of giant columns with graceful arches that separate the altar from the nave. The true ornament of the Cathedral is the altar of the fourteenth century and the baptismal font, the works of G. Vigolana (early twentieth century). In the Museum of the Cathedral are stored coronation solved Norwegian monarchs.

On the tower of the Cathedral is a viewing platform overlooking the magnificent views of the city and surrounding area.