The Valley of the Temples (Valle dei Templi) is a UNESCO World Heritage Site and one of the greatest legacies of ancient Greece. This parade of well-preserved Doric temples, just outside town, dates back to the fifth century BC and is what remains of the Greek city of Akragas.
The temples are spread along a rocky ridge a short way to the south of the medieval town centre, in a designated archaeological park. You can walk there, or catch a bus from the railway station. Food options are limited so you might wish to take a picnic lunch.