An elevated park overlooking the World Trade Center memorial opened in New York City on Wednesday. Modeled after Manhattan's popular High Line, the 1-acre, $50 million Liberty Park helps cover up a security building used to screen vehicles entering the site of the September 11 attacks. The park's most striking feature is its "Living Wall," a vertical garden featuring more than 22,000 plants. Located on the south side of the WTC site, the park surrounds the under-construction St. Nicholas Greek Orthodox Church, which is getting a new building designed by international starchitect Santiago Calatrava. The church's original structure was destroyed when the twin towers collapsed on 9/11.