A method of building a foundation, a foundation element (2), and a foundation for an antenna mast of a wireless communication system are provided. The foundation comprises at least three foundation elements (2). Each foundation element (2) comprises an elongated body (4). The elongated body (4) comprising a first end (6). At least one bar (16) extends from the elongated body (4) at the first end (6). An attachment arrangement (18) for the antenna mast is provided on the foundation element (2). The at least three foundation elements (2) are arranged to extend substantially symmetrically from a central portion (24) of the foundation (30). A central concrete portion is cast in the central portion (24) of the foundation (30) to join the at least one bar (16) of each of the three foundation elements (2).