Fodor's Expert Review Guayabo National Monument

On the slopes of Turrialba Volcano lies Costa Rica's only true archaeological site. The city, once home to possibly 10,000 people, was abandoned in AD 1400, probably because of disease or war. Starting from the round, thatch-roof reception center, guided tours will take you through the rain forest to a lookout from which you can see the layout of the excavated circular buildings. Only the raised foundations survive, since the conical houses themselves were built of wood. As you descend into the ruins, notice the well-engineered surface and covered aqueducts leading to a trough of drinking water, which still functions today.

Guayabo has been recognized by the American Society of Civil Engineers as a feat of Latin American civil engineering second only to Machu Picchu. The hillside jungle is captivating, and the trip is further enhanced by bird-watching possibilities: 200 species have been recorded.