Just across from the mainland, the ancient ruins at Corinth are a must-visit at the outset of any exploration of Greece's Peloponnese. But don't neglect to take the short drive up the hill to explore the ruined fort of Acrocorinth. It's a pretty easy hike from the parking area up through the imposing gates built by the many groups that have taken turns ruling this area over the centuries (Greeks, Turks, Franks, Venetians). Our 8-year-old managed the walk. The payoff is views of miles of the surrounding peaks and countryside. Based on our experience, the crowds will be much smaller than they are down at the main site of Corinth.