"I can't overstate the challenges that a site like this presents," says Alan Razak, principal of the Razak Co., which is in a co-venture with Athenian Properties LLC to form Razak/Athenian for special projects. The nine-story Lenfest Hall, formerly the Locust Club, is between two historic buildings and Razak/Athenian has elected to keep the original building's façade, which has meant constructing a temporary three-story wall to hold the structure up.

And none of that has anything to do with the acoustics. The Curtis Institute, which has a 120-student orchestra, has a very specific acoustical design that called for two layers of windows, on outdoor and one indoor, and more concrete than a normal development to prevent the building from shaking due to nearby train activity.

Another challenge, Razak says, was the mixture of rehearsal space and residential areas in the building for students. "The specifics of the needs of the conservatory take it out of the realm for standard educational institution development," he says of the project, which broke ground last week.