It is interesting to look at buildings as geometrical blocks. They are houses, libraries etc. for people to use, but they are also rectangular prisms with triangular prisms (the roofs) on top. Blocks of flats are often rectangular prisms stood on end. Clissold House is a rectangular prism with a half­cylinder at each end. Sister's House has an `M' roof, consisting of two triangular prisms side by side. Victo­rian bays in Allerton Road have octa­gonal pyramids on top.

An architect starts with a few blocks in mind. You may like to look at buildings and work out what blocks the arhiect had in mind.