With an estimated population of around 10,600, Conimbriga was not the largest Roman city in Portugal, but it was close, and it is the best preserved, remaining mostly unearthed until the 2000s. The city was inhabited between the ninth century BC and the seventh or eigh centuries AD. The most impressive things here are the wonderful mosaic floors that are virtually intact within the remains of their buildings. The site has a sense of a lived in town from a bygone era. It's easy to reach from modern Coimbra by car.