When the Romans decided to enclose their city of Tarraco in the 2nd century a.d., they built their walls on top of huge boulders. Only about a third of the original 3,500m construction still stands, and you can follow a garden-like path for about 0.8km (1/2 mile) of that length. Historic markers show the way; there are also opportunities to climb up onto the ramparts for views of the sea and country. As a reminder of the progression of history, you’ll find cannon placed in battlements by the Spanish in the early 18th century.