In architecture, a simple form of vault in which the stones are overlapped on each other and topped with a capstone. As distinguished from the true arch, it has no keystone and is not self-supporting; the thrust must be take up by massive walls. The corbel vault is therefore suitable for spanning only limited spaces. In the Mayan style, corbel vaults can support a roof or upper story. Corbel vaults and arches were useful in cultures that had not yet developed curving arches and other ceiling structures.