While designing the Villa in Sierra Leone, “surface drawings “ were applied to investigate elements of spatial changes. At a certain phase of the project, “corner”-s were identified, as representative elements of these changes. The drawing shows two basic types, denoted as A-Type and B-Type. The first is composed of three intersecting plane-fragments, all 90 degrees, meeting in one point. The B-Type has two 90 degrees and one 270 degrees plane-fragments composing a corner condition. At the design of the Peggy Guggenheim museum extension in Venice, Italy, these latter were employed. The “cubicum” in this sense is a by-product of an architectural investigation, where the question was asked: what happens with a cube, if only the B-Type corners surround it?