Karaağaç is 4 km southwest from the center of Edirne, across the river Meriç and opposite the Greek village Kastanies.

In 1890, the large Karaağaç railway station was built in the town, which also served Edirne, becoming the last train stop in Turkey to Europe.

The Treaty of Lausanne Monument and Museum, which opened in 1998, are located next to the former railway station.

Greek: Παλαιά Ορεστιάδα or Καραγάτσι[citation needed] When Greece held the town (1920-1923), Karaağaç was renamed Orestias, in remembrance of the ancient Thracian town with the same name, which probably lay near or at the site of present-day Edirne.

The Roman emperor Hadrian expanded the town into a city, gave it a strong fortification and renamed it Hadrianopolis.