Trajan conquered Dacia (roughly modern-day Romania and Moldova), and defeated the king Decebalus, who had defeated Domitian's forces. In the First Dacian War (101–102), the defeated Dacia became a client kingdom; in the Second Dacian War (105–106), Trajan completely devastated the enemy's resistance and annexed Dacia to the Empire. Trajan also annexed the client state of Nabatea to form the province of Arabia Petraea, which included the lands of southern Syria and northwestern Arabia. He erected many buildings that survive to this day, such as Trajan's Forum, Trajan's Market and Trajan's Column. His main architect was Apollodorus of Damascus; Apollodorus made the project of the Forum and of the Column, and also reformed the Pantheon. Trajan's triumphal arches in Ancona and Beneventum are other constructions projected by him. In the Second Dacian War, Apollodorus made a great bridge over the Danube for Trajan.