Houses of worship are some of the most enduring forms of architecture, but not all structures and congregations are considered equal when it comes to the ability to preserve their physical legacy. A 25-year-old Landmarks Conservancy group called Sacred Sites, however, has been successful at serving as a reassuring, guiding and supportive hand to churches, synagogues, and other houses of worship that need help shoring up deteriorating buildings. Sacred Sites is an arm of New York's Landmarks Conservancy. Over 25 years, it has given $7.5 million to 680 religious organizations across New York, including 200 city landmarks, according to The Wall Street Journal. There will be an open house involving 40 NYC sites to showcase the preservation work enabled by Sacred Sites the weekend of May 19-20. A list of the 140 statewide participants in the 2011 open house weekend includes St. Bart's on Park Avenue, the Old Broadway Synagogue in Harlem, St. Mark's Church-in-the-Bowery, and Tremont Baptist Church in the Bronx.