Sometimes the best monuments are the most modest ones. I accidentally came across Wellington's personal mounting block, which most passerbys would probably miss since a giant statue of King Edward VII rests beside this very spot. In the days of yore, horse blocks were used for assistance to mount and dismount a horse or a cart, especially for the young, elderly or infirm. They were especially useful for women riding sidesaddle, allowing a horse to be mounted without a loss of modesty.
Of course the thought of Napoleon's conqueror needing assistance to get up on his horse seems unflattering and ungallant, that is until you realize that the Grand Old Duke was getting up in age around 1830, so it stands to reason. In any event, I was pleasantly surprised to come across it.