The body of 20-year-old Gregor Smith was found at around 7am by a woman walking her dogs near the wall of the cathedral baptistery, located in the green square of Pizza del Duomo, also home to the iconic leaning tower, Il Messaggero reported.
His body was stretched out the grass with his head resting on his rucksack.
There were no evident injuries and his cause of death is currently unknown.
The dog walker immediately called an ambulance but medics could not revive the young man and pronounced him dead at the scene.
Smith was a resident in Montescudato, a small town outside Pisa, and had reportedly not been dead long before being found.
Police suspect he arrived in the square amid an early morning thunderstorm and are reviewing CCTV footage to try to establish if he arrived in the square alone.
He was reportedly on his way to meet a friend on his way to Liceo Russoli, where they both studied, but Smith never arrived.
His friend was questioned by police this morning.
The friend's father told Il Messaggero that Smith was “a really good kid.”
“He called my wife looking for my son last night and she spoke to him. She said he seemed normal and calm – there was nothing out of the ordinary.”