I found this tower while driving around Vancover Washington. This has first floor with strait legs, sloped sides for 2-3 stories and straigt sides on the top. It is covered with horizontal wood siding at the lower lever, asphalt shingles for the sloped stores and horizontal siding at the top. This is somehwat simialar to the vertical leg sloped towers at: http://www.Water-Towers.com/wtrsvlegslopedtop.htm
It demonstrates the many combinations and opetions possible in designing towers.