The red in Milan is for the Maldini family.  

Paolo Cesare Maldini is an Italian former professional footballer who played as a left back and central defender for A.C. Milan and the Italy national team, who is widely regarded as one of the greatest ever defenders, and as one of the greatest players of all time. 

Daniel Maldini is an Italian footballer who plays as an attacking midfielder for Serie A club Milan.  

Franco Baresi is an Italian football youth team coach and a former player and manager. He mainly played as a sweeper or as a central defender, and spent his entire 20-year career with Serie A club Milan, captaining the club for 15 seasons.

Рыбакова Елена, CC BY-SA 3.0 GFDL, via Wikimedia Commons