The area around Alphen aan den Rijn has been inhabited for 2000 years. In the Roman era, the Oude Rijn was the main branch of the Rhine River and formed the north border of the Roman Empire. Since the rule of Emperor Claudius (41–54 AD), divisions of the Roman army were stationed here. Consequently, several Roman fortifications were located along the Oude Rijn, including castellum "Albanianae" in the centre of Alphen. The Romans had also built the first bridge over the Oude Rijn. Alphen was therefore an important commercial site in the area until Germanic raids ended that in 240 AD.