Short answers, pulled from the story.
Hamburg, officially the Free and Hanseatic City of Hamburg, is the second-largest city in Germany after Berlin, with a population of over 1.9 million. It stands on the branching River Elbe at its confluence with the Alster and Bille, near the southern tip of the Jutland Peninsula, surrounded by Schleswig-Holstein to the north and Lower Saxony to the south.
Hamburg's rivers and canals are crossed by around 2,500 bridges, more than London, Amsterdam, and Venice put together, giving it more bridges than any other city in the world. The city grew up among the many streams, rivers, and canals where the Alster and Bille meet the Elbe.
The name Hamburg comes from a castle that Emperor Charlemagne ordered built in AD 808 as a defence against Slavic incursion. It rose on rocky ground in a marsh between the Alster and Elbe rivers and acquired the name Hammaburg, where burg means castle or fort.
Hamburg was a member of the medieval Hanseatic League and a free imperial city of the Holy Roman Empire, which its official name reflects. Its 1241 alliance with Lübeck is regarded as the founding moment of the Hanseatic League.
The Beatles lived and played in Hamburg from August 1960 to December 1962, gaining local acclaim before their widespread fame. One of the venues they performed at was the Star-Club on St. Pauli.
The Port of Hamburg is Germany's largest and Europe's third-largest, after Rotterdam and Antwerp, and ranks 17th worldwide. It handled 138.2 million tons of goods in 2016, and although it sits 110 kilometres up the Elbe, it is considered a seaport because it can handle large ocean-going vessels.
Hamburg has endured the Great Fire of 1842, which destroyed about a quarter of the inner city, the cholera outbreak of 1892 that killed about 8,600 people, World War II firebombing in 1943 that killed at least 42,600 civilians, and the North Sea flood of 1962 that killed more than 300 people. After each catastrophe the city recovered and often emerged wealthier than before.