The Romans did not take long to decide that Tarragona was worth fortifying. Scipio's army landed here in 218 BC during the war against Carthage, and in time the settlement of Tarraco became the capital of the Roman province of Hispania Citerior and later of Tarraconensis, and one of the largest cities in Roman Spain. Its walls started as a Republican fortification, with huge irregular blocks at the base, the so-called cyclopean masonry, which were later heightened and rebuilt in Roman and later periods. A good stretch survives in the Passeig Arqueològic, where you can walk along the top.
The city has a great deal more besides. The amphitheatre sits on a bluff above the sea, where, according to tradition, Christian bishop Fructuosus was burned in the third century. The Roman circus runs under the modern streets, and a ruined forum, a necropolis and an aqueduct, known as the Pont del Diable, lie around the outskirts. UNESCO listed the archaeological ensemble of Tarraco in 2000, and the city's human towers, the castells, are listed too, though you will see those only on festival days.
Riding in is easy but needs a little thought. From the coast road or the motorway you reach the upper town, with its cathedral and narrow lanes, and the old town is hilly and often closed to cars. Park in a designated motorcycle space near the walls and walk, and do not leave anything on the bike. Tarragona has plenty of fuel, from stations on the ring roads to the ones near the port, and the city is the obvious place to stock up.
The sea adds to the charm. From the Balcó del Mediterrani at the end of the Rambla Nova you can look out over the amphitheatre and the beach, and there are good seafood restaurants in the old fishermen's quarter at the harbour. Weekdays outside the high season are the quietest time. Constantí and Els Pallaresos, a few kilometres inland, are quiet small towns, handy for a break from the traffic.