Casa Rinconada, an Ancestral Puebloan site in Chaco Culture National Historical Park in northwestern New Mexico, stands on a ridge across from Pueblo Bonito and is one of only four isolated great kivas in Chaco Canyon. At 64 feet in diameter, it is the canyon’s largest excavated great kiva. Its ceremonial design includes a masonry firebox, inner bench, roof-support pits, masonry vaults, and 34 wall niches. A particularly unusual feature is a 39-foot underground passage cut through the ridge, thought to have enabled a sudden ceremonial entrance. Excavated in 1930 and 1931, it was partly reconstructed in 1933 and later preserved in 1955.