The invention relates to a tower of a wind power plant, having a lower part in the form of a lattice tower or truss tower with at least two corner bars, and an upper part in the form of a cross-sectionally substantially round tubular tower, wherein each particular corner bar is put together from a plurality of steel tube profiles that are connected together in the longitudinal direction. In order to achieve good transportability and easier assembly of the components of such a tower, the invention proposes a modular tower concept. According to the invention, each particular corner bar is in this case put together from at least three steel tube profiles which are provided with perforated flanges for holding screws, wherein the corner bars are connected together by cross struts and/or tension struts attached to the flanges, and wherein the steel tube profiles of each particular corner bar are spirally welded steel tube profiles.