Mangalia's two main draws are its ancient history and its therapeutic spa treatments. The city is built on the site of Callatis, a Greek colony founded in the 6th century BC, and archaeological remains — city walls, a necropolis, a mosaic floor — are visible in and around the modern town. The Callatis Archaeological Museum holds finds from the site and is one of the more interesting small museums on the Romanian coast.
The Esmahan Sultan Mosque is a remarkable survivor: built in 1590, it is the oldest mosque still in use in Romania and a tangible reminder of the Ottoman era when this part of Dobruja was part of the empire. For spa treatments — the thalassotherapy, sulphurous mud baths, and various cures that Mangalia is known for — the local clinics and hotels on the seafront offer packages year-round, though the peak season is summer.