Task: Question Answering
Input (English): Passage: Chaco Canyon lies at the geographic center of the San Juan Basin. It is located in northwestern New Mexico 60 miles (97 km) north of Interstate 40 and 130 miles (210 km) from Gallup, the nearest city. The continental divide is 20 miles (32 km) east. Chaco Canyon was created by the Chaco River, which cut several hundred feet into Chacra Mesa. The elevation of the sandstone canyon and the surrounding high-desert terrain is approximately 6,000 feet (1,800 m). Though most of the Chacoan sites are located at the bottom of the canyon, the group also includes some ruins not in the canyon proper, extending 35 miles (56 km) from Kin Ya'a in the south to Pueblo Alto in the north, and 20 miles (32 km) from Pueblo Pintado to the northeast and Peñasco Blanco in the southwest. In terms of water drainage and cultural affinity, the area is part of the San Juan Basin, which includes Mesa Verde in Colorado and Kayenta, Arizona.Chetro Ketl lies 0.4 miles (0.64 km) east of Pueblo Bonito, in an area that archeologists call downtown Chaco. Scholars theorize that the area may be an ancestral sacred zone demarcated by a low masonry wall that encloses Chetro Ketl, Pueblo Bonito, and Pueblo del Arroyo. Chetro Ketl's position is symmetrical to Pueblo Bonito; the buildings are equidistant from a north-south axis that runs across the canyon. Anna Sofaer proposed that many of the great houses in Chaco Canyon were constructed to emphasize astronomical alignments; during the minor lunar standstill, the full moon rises along Chetro Ketl's back wall.Chetro Ketl is located opposite a large opening in the canyon known as South Gap, which helped maximize the building's exposure to the sun while increasing visibility and access to the south. Its rear wall runs parallel to the canyon, and at less than 100 feet (30 m) from the cliffs its proximity allowed inhabitants to benefit from passive solar energy emanating from the rocks. Chetro Ketl is not perfectly aligned to the cardinal directions, but its nominal southerly orientation further enhanced solar exposure to its tiered rooms. 
Question: Which buildings are equidistant from a north-south axis that runs across the canyon?
Output (English): Chetro Ketl.