Ceide Fields in Ballycastle, County Mayo has been called the world's most extensive Stone Age site. Discovered less than 20 years ago, it is also one of Ireland's most significant archaeological finds, a 5,000-year-old farm unearthed in a blanket of bog. Visitors can take on-site tours of the field systems, enclosures, and tombs. A visitor center provides helpful background and displays. The nearby Cliffs of Ceide are a special attraction, too, composed on hundreds of layers of rock built up over millions of years.