Originally built in Romanesque style, the cathedral has been restored and extended several times, with Gothic, Renaissance and Baroque elements. Construction began in 1107, but the works were damaged and halted after an earthquake in 1117. Construction resumed in 1129, and the building was probably finished in 1160-1170. The main altar, dedicated to the city's patron saints Archelaus and Himerius, was consecrated in 1196.