Today's Tarragona is a very nice and quiet city on the coast just an hour south of Barcelona, and a very easy day trip, due to its great coastal location, medieval city center, and, of course, its Roman remains. Two millennia ago, this was Tarraco, the most important city in the Spanish provinces (and capital of Hispania tarraconensis, the largest province on the peninsula), and it's easy to see why the Romans chose this site for their capital. There are no really outstanding sites here, but what makes Tarragona very interesting and maybe even unique is the fact that it features a complete cross-section of a Roman city - it has an amphitheatre, a forum, a circus, a theatre, temples, administrative and residential buildings, defensive walls, a cemetery, a mausoleum, an aqueduct, and a triumphal arch. Most of these are rather well preserved. I especially liked the circus complex, the forum, and the amphitheatre. Several sites are outside the city centre (some quite far away). Of these, I visited the Tower of the Scipios (a funerary monument, not that interesting) and the Ferreres Aqueduct (locally known as the Devil's Bridge, set in a forest and very well preserved). The cathedral is also very impressive, but was closed when I was there. I have visited Tarragona twice, and my second visit in 2012 was much more exhaustive than the first one in 2005, which was just a brief excursion from Barcelona. I really liked the city, and if you are interested in Roman history, this is one of the better places to experience it.