Perrott's Folly is a tower built in 1758, by John Perrott, in Birmingham, England. This tower and the tower at Edgbaston Waterworks have been suggested as inspiration for The Two Towers in J.R.R. Tolkien's The Lord of the Rings. The tower stands 96 feet and seven stories tall, and is among Birmingham's oldest and tallest buildings.
Architecturally speaking, a folly is something built more for effect than utility. There are many folly towers (not the same as Fawlty Towers).
Portmeirion is another example of architectural folly. It is a fantasy village created, in miniature scale, by Sir Clough Williams-Ellis. Portmeirion is a location used in the TV series "The Prisoner".
Perrott's Folly has its own web site.