This strange and hidden Cult Cemetery located somewhere in Central Park, was built by the Cult of Gozer, supposedly to buried and honor their dead, especially those who strongly upheld their faith in their chaotic ancient god Gozer.
Central Park's Cult Cemetery is the central point of the four Mandala nodes (The first being the Library; the second, the Natural History Museum; the third, the Sedgewick Hotel and the fourth on Shandor Island) that the energy was supposed to have fed the Destructor Form of whoever rules and resides in this Mausoleum, which Ivo Shandor built for Gozer. Since Gozer failed his once favored disciple twice, Shandor decided to have all four nodes active in his own plans, so he could bring the Ghostworld into our world.
Once the symbol they found was identified as a Mandala, the Ghostbusters located the other three then shutdown the nodes and eliminated each of the node guardians (Azetlor, The Chairman, Spider Witch, and the Juvenille Sloar. Shandor kidnapped Ilyssa Selwyn (to use her blood) and shutdown the Containment Unit to use the energy from the escaped ghosts as an alternate energy source and managed to generate enough energy to raise up the Mausoleum in Central Park Cemetery. When the Ghostbusters finally got into the Mausoleum they found both Walter Peck and Ilyssa Selwyn were in there and the Mayor which was possessed by Shandor.