The invention provides an igloo-shaped structure formed from a plurality of rectangular shaped blocks having a rim and a trough molded therein. The rim has pins adjacent the corners of the blocks that engage apertures or holes fastening plates. Each fastening plate has four holes to enable it to snap together four blocks. Subsequent rows of blocks may have smaller dimensions so that the assembly curves inward forming the familiar domed shape of an igloo. Curved trapezoidal shaped blocks, also held together with fastening plates, are used to cap off the dome.