From the Wikipedia: The Eurymedon Bridge (Turkish: Oluk Köprü) is a Roman bridge over the river Eurymedon (modern Köprüçay) near Selge in Pisidia in southern Turkey. It is part of the road winding up from the coastal region Pamphylia to the Pisidian hinterland. Located 5 km north of the village Beşkonak in a sparsely settled area, the bridge crosses the Eurymedon high above the valley bottom.

The excellently preserved structure is 14 m long and 3.5 m wide (with a roadway of 2.5 m). The clear span of its single arch is c. 7 m, the thickness of its voussoirs, which were set without the use of mortar, 60 cm. The building technique and the sturdy stonework point to a construction date in the 2nd century AD, a time when Selge was flourishing.

42 km downstream at Aspendos, the Eurymedon is crossed by another extant old bridge.

The whole area north of Beşkonak village (including the Roman bridge, the antique city of Selge and the mountains north of it) has been declared a protected national park in 1973: the ‘Köprülü Kanyon Milli Parkı’; it has a surface area of 366 km².
The Canyon itself, which ends at the Roman bridge, is 14 km long; as such it is the longest in Turkey. In summer, it is visited massively by rafting groups (reportedly up to seven thousand people each day).

Correspondent: J.M.Criel, Antwerpen.
Source: Personal visits to Köprülü Kanyon and Selge/Altınkaya (1992 – 2004) & Vikipedia.