Milan’s grand old home turns 100 this weekend, and while it will soon be torn down one of the greatest players to grace it reflects on the noise and power of a unique stadium Alessandro Costacurta lasted 15 minutes of his first game at San Siro. He was, admittedly, not playing, but tagging along to watch his older brother’s favourite team. “I grew up in the province of Varese, north of Milan,” he says. “So as a kid I was a Varese fan. It was my brother who supported Milan. The first time I went…