Sanaa's Old City is renowned for its tower houses, which are typically built from stone and fired brick and can reach up to 8 stories in height. The doors and windows feature are decorated with plaster openings. They traditionally housed a single extended patrilineal family, with new floors being built as sons married and had children of their own. (New buildings would also sometimes be built on adjacent land.) The ground floor was typically used as grain storage and for housing animals. Most families no longer keep either animals or grain, so many homeowners set up shops on the ground floor instead. (This often leads to conflict with building inspectors, since doing so is prohibited by law.)