Summary: Foundations installed to stabilise huge buildings on often unstable ground, systems for hoisting enormous blocks of stone weighing hundreds of tonnes, development of increasingly monumental roofing methods, methods for cutting underground tunnels and systems to supply cities far from sources of water are just some of the solutions invented by Greek architects handed down by ancient writers, inscriptions or found through archaeological investigations. The Greeks tackled numerous architectural problems to meet the growing needs of the poleis and rich private patrons. The Romans nevertheless developed their own construction methods and techniques, first of all opus caementicium. This helped in the construction of vaulted roofs that ; as in the Pantheon - were unequalled for many centuries.