[ˈreθimno] , also Rethimno , Rethymnon , Réthymnon , and Rhíthymnos ) is a city of approximately 40,000 people in Greece , the capital of Rethymno regional unit on the island of Crete . It was built in antiquity (ancient Rhithymna and Arsinoe ), but was never a competitive Minoan centre.