Domes are curved roof structures without angles or corners that cover a large area without columns. The Romans were the first to realize the architectural potential of domes, constructing structures like the Pantheon and Superdome that had domes characterized by strength and interior space. Domes became an iconic part of Rome's skyline and were seen as works of art, with the Pantheon serving religious and later Christian uses continuously for over a millennium as one of the best preserved Roman buildings.