Graphic designer Paul Sahner has been taking pictures of New York's streets since he moved to the city nine years ago. He loves the feeling of capturing an ever-shifting urban landscape for posterity on his blog NYC Grid.

Inspired by the changing shops and street corners he saw while walking around, Sahner started a before-and after-series on NYC Grid. The photographer would match his own photos of New York City with old pictures from the Library of Congress or Flickr to showcase the transformation of the city's landmarks and streets.

"I don't share the hopeless sense of loss that many other NY bloggers and writers express," Sahner writes. "I don't dislike modern architecture, I don't fear gentrification, I enjoy change and relish new ideas. But I do feel there's something special about the time we're experiencing here. Once this time, this moment, has passed it will never return."

Over at NYC Grid, readers can use a toggle function to compare the old and new photos interactively. We've presented them here back-to-back in slideshow format so you can get the full effect of each image.