The Romans also introduced segmental arch bridges into bridge construction. The Limyra Bridge in southwestern Turkey features 26 segmental arches with an average span-to-rise ratio of 5.3:1, giving the bridge an unusually flat profile unsurpassed for more than a millennium. Trajan's bridge over the Danube featured open-spandrel segmental arches made of wood (standing on concrete piers). This was to be the longest arch bridge for a thousand years both in terms of overall and individual span length, while the longest extant Roman bridge is the long Puente Romano at Mérida. The late Roman Karamagara Bridge in Cappadocia may represent the earliest surviving bridge featuring a pointed arch.