What tree is this?
Attached is a photo. The trees are in York City Centre on Fossgate.
Answer
Based on your photograph, your tree looks like a Linden tree (Tilia sp.) We can't tell if it is the native American Basswood (Tilila americana), or the European Little Leaf Linden (Tiia cordata). The size of the leaf is one way to sort them out. The American Basswood is a larger leaf, about the size of an open palm, while the Little Leaf Linden is much smaller. Given your location, we would lean more toward the European Little Leaf Linden.
Lindens tolerate pollution, making them useful street plantings, which looks like the setting of your tree.