Why is Antwerp sometimes called the unofficial capital of Flanders?

Antwerp is often referred to as the unofficial capital of Flanders because it is located within the Dutch- (Flemish-) speaking part of Belgium and holds significant historical and contemporary importance to the region.1

Residents of Antwerp take this role very seriously, reflecting a deep consciousness of their city's prominence in both the past and the present. This sense of pride and a competitive attitude among the population have earned them the nickname Sinjoren, which is derived from the Spanish word señores. While the city of Brussels serves as the official capital of the Flemish Region, Antwerp’s status as a major global seaport, a center for the diamond industry, and a hub of fine arts reinforces its cultural and economic influence within Flanders.12