Across from the Plaza Calderón is the Iglesia del Sagrario, the old cathedral of Cuenca. Construction of this church began in 1557, using stones that were taken from the ruins of the old Inca city of Tomebamba. A tower was added in 1868, replacing an older tower that had been used by La Condamine and his expedition as the southern reference point in their efforts to determine the arc of the meridian. The church is now deconsecrated and serves as a museum for religious art.