As building materials became more understood, and skills developed amongst architects and builders, new construction techniques became possible. Domes, arches and vaults became regular features in Roman architecture, but a true dome was perhaps the pinnacle achievement of architects and builders of the time. They posed complex puzzles when it came to supporting the weight of the structure as it was being built, and it took time and a certain amount of trial and error for architects to perfect the system. The Pantheon in Rome is one of the best examples of a true dome and suggests that by AD128 architects had mastered the form.
