The German Architecture Museum is housed in a late 19th-century villa, which was converted in the early 1980s by the Köln-based architect Oswald Mathias Ungers. He created five levels, including a simple basement space with a visible load-bearing structure, a walled complex on the ground floor, and a house-within-a-house on the third floor. The museum features a wealth of documents on the history of architecture and hosts debates on its future. Each year, several major and numerous smaller exhibitions highlight issues in architectural history and current topics in architecture and urban design, including sustainability. A permanent exhibt features the most comprehensive collection of model panoramas in the history of German architecture.