Hamburg’s name derives from the Hammaburg whose name is thought to derive from *ham- “angle, angular terrain by rivers, bay”, as well as burg, “elevated fortification, settlement”. Here is it overlaid on the current terrain, constructed in the 8th century, though settlement is attested to the 4th century BC. First mentioned in writing 834, likely previously seat of local Saxon nobility, then taken over. Previously known to the Romans as Treva. That early 800s date matches the direct aftermath of Charlemagne’s Christianisation-by-genocide of the Saxons, with the first church being constructed in 810. Also, the writ it was first mentioned in happens to be the one that sets up Ansgar as Bishop of Hamburg.

Republic since 1292. Trade-wise where the Ossenpadd and Elbe meet, in case you wonder who had the genius idea of building a harbour city inlands: Since about the bronze age (2000BC thereabouts) up until industrialisation it has been a vital trade route, going straight through Hedeby where you also get a competitive connection to the Baltic Sea, a role which was later inhabited by Lübeck.