LAFAYETTE -- Acalanes High School junior Marc Davis, a member of Boy Scout Troop 204 of Lafayette, created an iOS smartphone application for an independent walking tour of Lafayette landmarks for the Lafayette Historical Society.

The tour begins at the society, at 3491 Mt. Diablo Blvd., on the lower level of the Lafayette Library and Learning Center. Along the way, visitors will hit notable landmarks in Lafayette and be provided with information about them. Marc and his fellow Scouts took a docent-led tour to take photos, mark GPS coordinates and record verbal information for the app. They also researched and collected old photos from the Historical Society to include in the final product.

Marc took all of this data, did some iPhone app programming magic and released "Lafayette Historical Walking Tour," available for free in the Apple app store on iPad, iPhone and iTouch.

The user can put the app into "auto" mode and when approaching a historical site, the audio tour will automatically begin, triggered by GPS location.

Old and new photos are overlaid with the ability to slide back and forth between them to gain an understanding of how the site has changed over the years.

Visit www.lafayettehistory.org for more information.