On top of the Wellington Arch.
From Wikipedia:
Wellington Arch, also known as Constitution Arch or (originally) the Green Park Arch, is a triumphal arch located to the south of Hyde Park in central London and at the north western corner of Green Park (although it is now isolated on a traffic island). The arch, and Marble Arch to the north of Hyde Park, were both planned in 1825 by George IV to commemorate Britain's victories in the Napoleonic Wars. The Wellington Arch was also conceived as an outer gateway to Constitution Hill and therefore a grand entrance into central London from the west. The presence of a turnpike gate at this point had led, in the eighteenth century, to a strong perception that this was the beginning of London (reflected in the nickname for Apsley House as "No 1, London") and the Arch was intended to reflect the importance of the position.
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The Wellington Statue was removed to Aldershot at the same time and was eventually replaced, in 1912, by a huge bronze quadriga designed by Adrian Jones. It is based on a smaller original which caught the eye of Edward VII at a Royal Academy exhibition. The sculpture depicts the angel of peace descending on the chariot of war. The face of the charioteer leading the quadriga is that of a small boy (actually the son of Lord Michelham, the man who funded the sculpture). The statue is the largest bronze sculpture in Europe.
