A cage, such as a bird or other animal cage, incorporates a number of integral fastening elements that facilitate assembly of vertical side panels and top panels of the cage without the use of hand tools. Pin and aperture fastening elements are combined with headed pin and keyhole slot fastening elements to facilitate attachment of adjacent panels to one another. U-shaped locking clips are also employed to insure that the assembled side panels cannot move vertically relative to one another. The top assembly of the cage uses tab and slot type and U-shape clip type fastening elements to facilitate assembly.