Crews have unearthed remains of the roundhouse that once stood in Salem MA under a current MBTA parking lot. The Historical Commission unearthed the roundhouse remains in early December 2012. Construction of a new parking garage on the site is scheduled to begin in the second quarter of 2013 and to finish in September 2014. If you want to see these remains, better do it now before ther are covered forever!
Wikipedia roundhouse site photo 12/9/12
Aerial photos of the site from historicaerials.com