Following compression of the inner city, and completion of the ICE-embankment after 10 years of work are the impulses for the courtyard building of the Hannover board of trade. Adjacent to the main train station, the annex intelligently uses valuable space resources in a heterogeneous yard-idyllic manner for a necessary addition to the office spaces. The core of the new building is a variable-use attic storey opened by a spiral staircase. A spacious attic terrace and hall, used as conference- and seminar space, invite users to stay with a comfortable ambient appearance. Wall-panelling and mobile mahagony louvers in the floor, combined with basaltlava-slabs, soften the daylight and produce a haptic club-atmosphere.