I've never noticed a particularly strong odor emanating from Callery pear flowers, but many people apparently find their scent unbearable. (See, for example, this article entitled "Meet the tree that's making your neighborhood smell like Semenville, USA".)
Smells aside, perhaps the noblest of all the city's Callery pears is the 9/11 "Survivor Tree". After 9/11, it was "the last living thing to come out of the rubble of ground zero — a charred stump that, to an untrained eye, looked dead." The tree was taken to a nursery in Van Cortlandt Park in the Bronx to recuperate. After almost a decade there, having returned to excellent health (and having survived another brutal assault — by Mother Nature this time), it was moved back to the World Trade Center, where it now stands amid a grove of swamp white oak trees at the National September 11 Memorial plaza.