We construct a homological approximation to thepartition complex, and identify it as the Titsbuilding. This gives a homological relationshipbetween the symmetric group and the affine group,leads to a geometric tie between symmetric powersof spheres and the Steinberg idempotent, andallows us to use the self-duality of theSteinberg module to study layers in the Goodwillietower of the identity functor. 2000 Mathematics Subject Classification:55N25, 55S15, 20B30, 55P25.