The cenotaph (or what’s left of it, the decoration is now in the Antalya museum) of Gaius Caesar, adopted son of Augustus, who died here in 4 AD. The Wikipedia has "The cenotaph of Gaius Caesar. From the Wikipedia: “Gaius Julius Caesar (20 BC – 21 February AD 4), most commonly known as Gaius Caesar or Caius Caesar, was the oldest son of Marcus Vipsanius Agrippa and Julia the Elder. He was born between 14 August and 13 September 20 BC or according to other sources in 23 September 20 BC with the name Gaius Vipsanius Agrippa, but when he was adopted by his maternal grandfather Roman Emperor Augustus, his name was changed to Gaius Julius Caesar.