Gallia Belgica (Belgic Gaul) was a province of the Roman empire located in Belgium, in the northern and eastern parts of Roman Gaul.It began as one of the three main provinces of Gaul (known as the Tres Galliae the other two being Gallia Aquitania and Gallia Lugdunensis) described by its Roman conqueror Julius Caesar. An official Roman province was later created by emperor Augustus in 22 BC. The capital of Belgica Prima, Trier, became an important late western Roman capital.