The first representatives, 10-12, of the new species of double-decked cyclopropenonophanes were synthesized by cycloaddition reactions of dichlorocarbene to alkynylenecyclopropenonophanes 7-9 followed by hydrolysis as well as in an alternative route involving hydride abstraction from dichlorotricycloalkadienes 16 and 17 to dichlorocyclopropenyliophanes and in situ hydrolysis of the latter. The X-ray analysis of [3.3]cyclopropenonophane 10 reveals a considerable tetragonalization of the bridgehead carbon atoms, indicating a significant deformation of the cyclopropenone moieties in the phane corset. According to ab initio calculations, the π orbitals of the cyclopropenones display transannular interactions of nearly the same scale as found in 7.