Final answer:
Lübeck was the de facto capital of the Hanseatic League, a major commercial and defensive alliance in medieval Europe. Its prominence was due to its strategic location and influential legal structures that served as a model for other cities in the League.
Step-by-step explanation:
The city of Lübeck was historically the de facto capital of the Hanseatic League, an extensive confederation of merchant guilds and market towns in Northwestern and Central Europe.
Credited with achieving a commercial monopoly over much of the Baltic Sea and the North Sea during the late Middle Ages, the League facilitated economic growth through cooperation and mutual defense among its member cities.
Lübeck's prominent role within the League can be attributed to its strategic location and the fact that its internal institutions and laws provided a model for the entire network of the Hanseatic cities.