Didymoteicho, the short-lived capital of the Byzantine and Ottoman empires, after the conquest of Thrace, was built on the twin hill opposite Plotinoupoli after the latter’s decline in the 8th century. The Byzantine imposing walls of Didymoteicho stand as witnesses to its glorious historic past, with their many towers and castle gates, that bear symbols and walled-in monograms of the Byzantine rulers. Byzantine churches and funereal imperial chapels underline the strategic role the town played in the 14th century, when it was visited by Emperor Ioannis VI Kantakouzinos. One of the extant buildings from the Ottoman past of Didymoteicho is the oldest and most beautiful mosque on European territory, which was built in 1420. The narrow streets of the old town, picturesque traditional and neoclassical houses and post-Byzantine churches underline the beauty and uninterrupted course of Didymoteicho which still bustles with life.