Actor and his son were in Italy to find their roots
James Gandolfini died of a heart attack after spending a day sightseeing in Rome in sweltering heat at the start of a trip during which he wanted to discover his Italian roots.
The 51-year-old actor suffered a cardiac arrest in the bathroom of his luxury hotel late on Wednesday, and was discovered by his 13-year-old son, Michael.
The teenager raised the alarm by phoning the hotel's reception, and staff in turn called emergency paramedics.
Gandolfini, who also starred in 'Zero Dark Thirty', the film about the killing of Osama bin Laden, had spent much of the day visiting Rome's best-known attractions with his son from his first marriage, and his sister, Johanna Antonacci.
The capital was hit by a heatwave, with temperatures soaring above 32C, which saw sunburnt tourists seeking relief in fountains.
It is not known whether the heat was a factor in the death of the actor, but he was well known for his girth, and once described himself as "a 260-pound Woody Allen".
After visiting Rome, Gandolfini had been due to travel to Sicily at the weekend to attend a film festival, where he was to receive an award.
Edie Falco, the actress who played Tony Soprano's wife, Carmela, in 'The Sopranos', remembered him as a "man of tremendous depth and sensitivity".
"I am shocked and devastated by Jim's passing," she said in a statement. "I consider myself very lucky to have spent 10 years as his close colleague."
Gandolfini's second wife, Deborah Lin, was reported to be on her way to Rome. The couple have an eight-month-old daughter.