Romanesque may first be sensed in new structural developments.. Sophisticated but unsatisfactory attempts to vault the great basilican naves safely, with elements of Roman, Byzantine, or Eastern origin, impelled progressive Romanesque engineers, from about 1090 onward, to invent a new type of ribbed groin-vaulted unit bay, using pointed arches to distribute thrust and improve the shape of the geometric surfaces. Fifty years of experimentation produced vaulting that was light, strong, open, versatile, and applicable everywhere--in short, Gothic vaulting. A whole new aesthetic, with a new decorative system--the Gothic--was being evolved as early as 1145. The spatial form