I guess most people know that the Monument was designed by Sir Christopher Wren as a memorial to the Great Fire of 1666, its 202ft (61m) being the distance from its base to the bakery in Pudding Lane where the fire started. The tallest free-standing stone column in the world when it opened in 1677, it has been repaired every 100 years since. Currently closed for the latest renovations - which will include facilities for firework and laser displays - it will re-open in December 2008.

(The San Jacinto Monument, Texas, opened in 1939 and is 600ft tall, while the Washington Monument (1884) is 555ft high - so don’t believe any guide who says the Monument is STILL the highest stone monument in the world.)

What you may not know is that Wren’s collaborator Robert Hooke (1635-1703) originally designed the interior as a giant telescope, with lenses at the top and bottom giving views from a small laboratory at the base. The flaming urn on top has a small trapdoor that opened to allow a view of the sky.(In fact, he - and not Wren - almost certainly designed the whole structure.) Robert Hooke was Surveyor of the City of London after the Great Fire, a founder member of the Royal Society and a noted experimenter. Besides his telescope, he used the Monument’s 311 steps - all exactly six inches high - to measure the effects of different heights on atmospheric pressure.

Hooke was also involved in building the Royal Observatory at Greenwich. He gave his name to Hooke’s Law (the extension of a spring is proportional to the weight hanging from it), built the first reflecting telescope and invented the universal joint (used by him on a telescope to track the sun but now a vital component of motor vehicles and still called a Hooke’s Joint). He also invented the iris diaphragm for cameras, the balance wheel for watches and first used the word 'cell' in biology. Quite a man.

www.themonument.info/

www.roberthooke.org.uk