The Providence Preservation Society (PPS) will celebrate twenty years of its Most Endangered Properties (MEP) program with the opening of the Most Endangered Properties 20th Anniversary Photo Exhibit onThursday, May 28th from 5 p.m.-8 p.m. in the atrium of the Peerless Building at 150 Union St. in downtown Providence. The project features images by the city’s most talented photographers that beautifully document the history of the Endangered Properties list and presents a Retrospective of Providence’s twenty most significant preservation stories from the last two decades – highlighting the successes of the program and exploring lessons learned from buildings that have been lost.