The Monument is 202 feet tall ,This was also designed by Christopher Wren , and erected between 1671 and 1667 . It was the cities memorial for the Great Fire in 1666 . The Monument tallest single stone column in the world and contains a spiral staircase leading to a viewing platform from which you can see some remarkable views of the city . The top of the monument is reached by climbing up the narrow winding staircase of 311 steps . A cage was added in the mid-19th century at the top of the Monument to prevent people jumping off, after six people had committed suicide between 1788 and 1842 .