  An axiomatic characterization of buildings of type $\CC_3$ due to Tits is
used to prove that any cohomogeneity two polar action of type $\CC_3$ on a
positively curved simply connected manifold is equivariantly diffeomorphic to a
polar action on a rank one symmetric space. This includes two actions on the
Cayley plane whose associated $\CC_3$ type geometry is not covered by a
building.
