AC Milan and Inter Milan — fierce cross-city rivals — have shared the San Siro stadium as their home ground for decades, an arrangement that's unusual for such a historically intense rivalry.
A practical, historical arrangement
Rather than each club building a separate stadium, San Siro has long served as the shared home ground for both Milan clubs, with match dates and colors (each club has its own end and iconography on derby day) distinguishing whose 'home' game it is.
The Derby della Madonnina
The Milan derby, played in the very same stadium both clubs call home, creates a genuinely unusual rivalry dynamic — the exact same physical venue transforms identity depending on which club is hosting.
An arrangement facing possible change
Both clubs have at various points discussed separate future stadium plans, meaning the decades-long shared arrangement isn't necessarily permanent, even though it's been the status quo for a very long time.
Do other cities have rival clubs sharing one stadium?
It's relatively uncommon at the top level of European football specifically — the Milan arrangement is one of the most prominent examples, though shared stadiums do exist in various forms in other cities and lower divisions worldwide.