O'Neill cylinder

An O'Neill cylinder is a hypothetical space colony type consisting of a giant cylindrical spacestead. The original concept proposed by NASA would be 8km\5mi in diameter with a length of 32km\20mi, but other sizes would be possible. The entire internal surface of the cylinder (with the exception of the ends) could be land, or there could be strips of land alternating with strips of some transparent or translucent material.