In the years since he began the project, Sahner began to feel overtaken by a sense of urgency to document the city exactly as he was seeing it in any particular moment.
'I'm not sure if it's simply that I'm paying attention more than I used to or if there is an actual shift going on, but the rise and fall of neighborhoods seems to be taking up an accelerated pace,' he says.
'Once this time, this moment, has passed it will never return.'
Sahner's project, he says, is not merely about documenting streets and buildings, but rather moments in time.
In this spirit, Sahner began making fascinating 'Before and After' shots. Pairing his own contemporary photographs with shots taken from the beginning to the end of the 20th century, Sahner creates a fascinating contrast of the same place in different eras.
Sahner's website
NYC Grid adds another layer of interest to the comparison with a toggle function that allows users to slide back and forth across the photograph revealing more or less of the before and after images.