Ten years ago this month, demolition began on the long-condemned Palast der Republik (Palace of the Republic) in Berlin, once the showpiece of the East German government. Opened in 1976, it was built on the site of the demolished City Palace, which had been severely damaged in World War II. The building with its copper-tinted windows, once home to the GDR People’s Chamber, auditoriums, theaters, even a disco, occupied an important site in the historic center of the reunified capital city.   Now taking shape on the same site is the Berlin Palace-Humboldt Forum, designed to replicate the facades of the City Palace, it will contain exhibition and performance space, museums and archives and part of Humboldt University.