Abstract: A puzzle including a plurality of pieces each having a subset of coded symbols on its top and bottom surfaces. The pieces are adapted to fit together to form a closed structure when a plurality of symbols in the respective subsets of adjacent pieces match each other. In one embodiment, the pieces are arcuate blocks each having symbols formed by a plurality of peg arrangements extending from the top surface of the blocks, and correspoding aperture arrangements in the bottom surface of the block. The blocks are arranged end-to-end to form several courses, and the courses are stacked above each other with the blocks of one course overlapping two blocks of each adjacent course. However, the blocks may overlap each other only when their aperture arrangements match the peg arrangements of the blocks below. In another embodiment of the invention, the pieces are formed by a plurality of arcuate strips each having a plurality of spaced apart symbols.