"That the city of Bergamo is composed of two parts can be easily appreciated. There is the Città Alta (Upper Town), built up on the hills, which is the "city" by definition, and the Città Bassa (Lower Town), which is a lively financial, industrial and administrative centre of national importance. The two parts are separated, both physically and symbolically, by the powerful Venetian Walls, which were built by the Serenissima Republic of Venice in the second half of the 16th century to defend the city, which was the farthermost centre on the Mainland, close to the border with Milan's territory. Bergamo (from berg-heim, i.e. the hill-town) was probably founded by Celtic populations, which settled on the hills looking onto the plan at the outlet of the pre-Alpine valleys of the Brembo and Serio rivers, two tributaries of the Adda river. The first historical evidence dates back to the year 223 b.C., when it is certain that Roman military forces were present in this area. In 49 b.C., Julius Caesar granted the status of Municipium to the town, which started its slow Romanisation process. Bergomum, which is the Latin name of Bergamo, was provided with major public buildings, which are currently no longer visible even though some remains often surface up on the occasion of excavations and diggings. Walls were also built up, parts of which are still extant; they were re-used for the new, larger Medieval fortifications with some enlargements and restorations. Indeed, the fortifications had remained relatively intact after the fall of Rome, so much so that Bergamo had been referred to as "operibus munitae" [surrounded by walls] by the historians reporting on the Gothic war in the mid-6th century. .."
Source: UNESCO World Heritage Tentative List
Upper Town of Bergamo. Thanks to Jean-Pierre of France for mailing from Bergamo in August 2016.