DDT was banned in the 1970s and efforts were made to increase breeding success by providing artificial nesting sites for the birds and reintroducing breeding birds into territories which had been devoid of falcons for decades. Over the last forty years they've made a gradual comeback and can now be found nesting on almost every bridge on every major river in the eastern United States. They also nest in urban areas on tall buildings, feeding mostly on medium-sized birds like pigeons and gulls which are abundant in cities and along large rivers.
An office building in Harrisburg, PA has hosted a nesting pair for several years and four "falcon cams" have been set up on the site (called an aerie) enabling viewers to watch the progress of the falcons, which mate for life, at close range as they raise their brood.
The birds are presently preparing to lay their eggs and are active around the nest during the day. The Harrisburg cam can be accessed here and if you click on the link during daylight you may well find yourself eyeball to eyeball with a peregrine. Enjoy.