Hundreds of ancient standing stone monuments like dolmens, menhirs and megalithics Tumulus were erected during the prehistoric period in Galicia, amongst the best-known are the dolmens of Dombate, Corveira, Axeitos of Pedra da Arca, menhirs like the "Lapa de Gargñáns". From the Iron Age, Galicia has a rich heritage based mainly on a great number of Hill forts, few of them excavated like Baroña, Sta. Tegra, San Cibrao de Lás and Formigueiros among others. With the introduction of Ancient Roman architecture there was a development of basilicas, castra, city walls, cities, villas, Roman temples, Roman roads, and the Roman bridge of Ponte Vella. It was the Romans who founded some of the first cities in Galicia like Lugo and Ourense. Perhaps the best-known examples are the Roman Walls of Lugo and the Tower of Hercules in A Coruña.