Delos is a tiny uninhabited island in the Cyclades and one of the most important archaeological sites in all of Greece. In antiquity it was considered the birthplace of Apollo and Artemis, and became one of the most sacred sites in the Greek world — a major religious and commercial centre whose ruins now spread across virtually the entire island. Nobody lives here permanently; it is accessible only by boat from nearby Mykonos.
The site is extraordinary: you can walk through the remains of temples, a theatre, and the famous Terrace of the Lions — five archaic marble lions that have stood guard over the Sacred Lake since the 7th century BC. The Archaeological Museum on the island houses finds from the excavations including the original lions (replaced on the terrace by copies). Delos is included on the UNESCO World Heritage List as part of the broader Cycladic landscape. Plan at least two to three hours for a serious visit.