The Mandans, along with the Hidatsa and the Arikaras, built dome-shaped houses of logs and earth called earthlodges. Today, all that remains of the earthlodges on the surface are circular depressions. Men usually decided how large an earthlodge would be, and women did most of the building. Construction began with a wooden framework that was covered with layers of willow branches, grass, and finally earth. Building one earthlodge took about 150 trees. Earthlodges typically measured 35 to 45 feet in diameter, though they ranged from 20 to 65 feet, and housed a family of eight to twenty people. They were built close together. A typical earthlodge had a large communal fire pit at the center of the house. Four large vertical posts formed a square around the fire pit and supported most of the roof's weight. Cross beams between the posts and rafters extending from the center to the outer edge, like spokes in a wheel, also supported the roof. Around the perimeter, a series of about a dozen shorter vertical posts supported the roof's outer margin.