Xanthos or Xanthus, also referred to by scholars as Arna, its Lycian name, (Ksantos, Lycian: 𐊀𐊕𐊑𐊏𐊀 Arñna, Ξάνθος, Latin: Xanthus) was an ancient city near the present-day village of Kınık, in Antalya Province, Turkey. The ruins are located on a hill on the left bank of the River Xanthos. The number and quality of the surviving tombs at Xanthos are a notable feature of the site, which, together with nearby Letoon, was declared to be a UNESCO World Heritage Site in 1988.
Xanthos was a centre of culture and commerce for the Lycians, and later for the Persians, Greeks and Romans who in turn conquered the region. As an Lycian important city, Xanthos exerted architectural influences upon its neighbours; the Nereid Monument directly inspired the Mausoleum at Halicarnassus in the Caria region.
Two Lycian heroes of the Trojan War, Sarpedon, is described in the Iliad as an ally of Troy.
The acropolis of Xanthos dates from the 8th century BCE. The city was mentioned by ancient Greek and Roman writers. The Greek historian Strabo noted that Xanthos was the largest city in Lycia. The important religious sanctuary of Leto at Letoon, south of Xanthos, dates from the late 6th century BC, and was closely associated with the city and linked by a sacred road.
The Greek historians Herodotus and Appian both described the conquest of the city by the Median general Harpagus on behalf of the Persian Empire, According to Herodotus, the Persians defeated a small Lycian army in the flatlands to the north of the city in 540 BC. The Lycians retreated into the city, which Harpagus then besieged. The Lycians destroyed their acropolis, and killed their wives, children and slaves, before engaging the enemy in a suicidal attack.
During the Persian occupation, a local leadership was installed and by 520 BC it was minting coins. By 516 BC Xanthos had been included in the first nomos of Darius I in the tribute list.
From Telmessos the army of Alexander the Great marched over the mountains to Xanthos.