This spectacular 17th-century cathedral on the Plaza de Armas has a religious-art museum inside. The moody facade doesn’t quite prepare you for the intricacy of the interior, with its elaborate gold-leaf altar being one of the best examples of the baroque- churrigueresque style (in which cornices and other intricate, Spanish-influenced workmanship mingled with Andean influences, often evinced by the wildlife depicted). These altars also demonstrate how the concept of the retablo, the ornamental religious dioramas that are Ayacucho's most famous export, came about. The word originally meant 'behind the altar' in reference to the statues placed within cases and set behind early altars. Ten such altars are contained here. Ask at the shop at the entrance about visiting the cathedral's catacombs.