We address the problem of multi-robot area coverage and present a new approach in the case where the map of the area and its static obstacles are known and the robots have a limited visibility range. The proposed method starts by locating a set of static guards on the map of the target area and then builds a graph called Reduced-CDT, a new environment representation method based on the Constrained Delaunay Triangulation (CDT). Multi-Prim's is used to decompose the resultant graph into a forest of partial spanning trees (PSTs). Each PST is modified through a mechanism called Constrained Spanning Tour (CST) to build a cycle which is then assigned to a covering robot. Subsequently, robots start navigating the cycles and consequently cover the whole area. The proposed approach is complete provided that at least one of the robots operates correctly.