Borussia Dortmund's absolute biggest and most historic rival is FC Schalke 04, hailing from the nearby city of Gelsenkirchen in the Ruhr valley. Matches contested between these two bitter regional adversaries are universally known as the Revierderby (Ruhr Derby), widely regarded as one of the most intense, passionate, and fiercely contested football rivalries in world sport. The animosity stems from geographic proximity, industrial working-class roots, and decades of competing for local and national supremacy. Additionally, Dortmund shares a modern competitive rivalry with Bayern Munich, dubbed Der Klassiker, driven by battles for Bundesliga titles.