Haus Carstanjen

[1] From the summer of 2006 many of the UN organisations relocated to a new campus in the renovated Langer Eugen tower, leaving the UNFCCC secretariat resident in Haus Carstanjen.

In November 2015, the German Federal Government welcomed the United Nations System Staff College - Knowledge Centre for Sustainable Development in Haus Carstanjen.

[2] The original castle consists of an angular, Neo-Gothic three-story building, with two circular turrets, roofed conically in grey slate, mullioned windows, and colonnaded galleries.

Carstanjen was a skilled collector and filled his residences in Cologne, Bad Godesberg, Plittersdorf and Berlin with Old Masters by Frans Hals, Rembrandt van Rijn, Aelbert Cuyp, and with antique furniture, wall tapestries, arms and armour, which his agents sourced from across Germany and auctions in Paris and London.

It takes the form of a large rotunda, similar to a small pantheon in the style of ancient Rome, with a domed roof over several floors of rich internal and external decoration.