It is a lime tree (not the citrus type of lime), Tilia. Americans would use the name linden.
It looks to be in a garden/park setting, so there are more possible species and hybrids than if it was in the wild.
It is close to Tilia platyphyllos, the large-leaved lime, but it could be Tilia × europaea, common lime. Both are variable in their characters to some extent. If there is a 'ruff' of suckers arising from the base of the trunk (not visible in your photos), it would be the Tilia × europaea.