It wasn't just in Milan, it was IN THAT SAME BUILDING.
The date was February 5, 2001. Mrs. Siglinde Sinner had just returned home from her first-trimester ultrasound, when she switched on the TV and... OK, OK, whatever.
But the 2001 Milan ATP was indeed held at the renovated Palalido, for the very first time (recent editions, prior to the 3-year hiatus when the event was moved to London, had been played at the much bigger Palatrussardi and Assago Forum). The tournament existed until 2004. By 2010, the Palalido had fallen into disrepair, and for years efforts to renovate it proved unsuccessful. Giorgio Armani had personally offered to fund renovation with the intent of moving his basketball team there, but he eventually pulled out frustrated by delays and bureaucratic complexities. Finally, in 2018, work got underway. In the summer of 2019 the building was reopened as the Allianz Cloud. The 2019 Next Gen ATP FInals was the very first tennis event ever to be held in the new facility.
Just a bit more detail for those punctilious omenologists...