Pre-History and Roman era
Bellinzona has always occupied an important geographic location in the Alps. Several key alpine passes, including the Nufenen, St. Gotthard, Lukmanier, San Bernardino and the Poebene, all meet in the area around Bellinzona, making it a key trading center.
While the region has been occupied since the early Neolithic age it wasn't until the late 1st century BC that a fort was built in the area during the reign of the Roman Emperor Augustus. While the fort fell into disrepair in the following centuries, it was rebuilt and greatly expanded in the 4th century AD. During the reign of Diocletian and Constantin a chain of castles and watchtowers were built to protect northern Italy from invasion. Bellinzona's location was recognized as a key point in the defenses and a large castle was built to protect the walls. The town that grew up around the fortifications was known as Bilitio.
Following the collapse of the Western Roman Empire the successor states, which included the Ostrogoths around 500 AD, the eastern Byzantine Empire towards the middle of the 6th century, and the Longobards from 568/70, all took control of Bellinzona and used the castle to assert control of the surrounding passes. Under the Longobards, Bellinzona became the site of a permanent garrison to protect the region from raids by the neighboring Frankish and Alemannic tribes. From Bellinzona the Longobards controlled the traffic on the important trade route from Varese over Ponte Tresa, the Monte Ceneri Pass, Biascaand finally over the Lukmanier Pass into Chur. Some researchers believe that Bellinzona may have been the capital of a county that included most of the valleys in Ticino.
Early Middle Ages
At around 774 the Frankish Kingdom (that would become the Carolingian Empire) gained control of the Ticino valley including Bellinzona.
About 2 centuries later the Holy Roman Emperor Otto III, seeking to restore the power