A few bridged [16]annulene perimeters have been reported although the parent [16]annulene is unstable. The same challenge applies in the case of the [12]annulene perimeters. Most molecules we test have distorted structures with significant bond-length alternation. The best example we identified is the bridged [16]annulene perimeter shown at the bottom in Figure , where the first excited state is almost degenerate with the triplet of the same electron configuration.