Dorylaeum was an ancient city in Anatolia. It is now in ruins near the city of Eskisehir , Turkey.
The city existed under the Phrygians but may have been much older. It was a Roman trading post, and a bishopric under the Byzantine Empire. After the Battle of Manzikert in 1071 it was taken by the Seljuk Turks.
Dorylaeum was the site of two battles during the crusades. In 1097, during the First Crusade, the crusaders defeated the Seljuks there, in their first major victory. During the Second Crusade it was the site of a major defeat, which effectively ended the crusade. See Battle of Dorylaeum.
Byzantine emperor Manuel I Comnenus fortified Dorylaeum in 1175, but the Turks recaptured it in 1176 after the Battle of Myriokephalon. In 1240 it was taken by the Ottomans.