Apulon (Apoulon, Apula) was a Dacian fortress city close to modern Alba Iulia, Romania from where the Latin name of Apulum is derived. The exact location is believed by many archaeologists to be the Dacian fortifications on top of Piatra Craivii, Craiva, Cricău, about 20 km north of Alba-Iulia.
Apulon was an important Dacian political, economic and social center, the capital of the Apuli tribe. It was first mentioned by the Ancient Greek geographer Ptolemy in his Geographia, under the name Apulon. It is also depicted in the Tabula Peutingeriana as an important city named Apula, at the cross road of two main routes: one coming from Blandiana, the other from Acidava. The two roads merge at Apula, with the next stop on the route being Brucla.
After the southern part of Dacia became a province of the Roman Empire, the capital of the Dacia Apulensis district was established here, and the city was known as Apulum. Apulum was one of the largest centers in Roman Dacia and the seat of the XIII Gemina Legion. The castra at Apulum is the largest in Romania, occupying 37,5 ha (750 x 500 m).