The Lion's Mound at Waterloo was completed in 1826.
Although King William I ordered the monument in 1820, the visible mound and its monumental lion took several more years to finish. Construction itself took place between 1823 and October 1826, when the lion statue was hoisted onto its pedestal. The delay explains why 1820, despite being an important date, is not the completion year.
The monument is a huge artificial hill at Braine-l'Alleud in Walloon Brabant, Belgium. Its summit provides a wide view over the former battlefield, and the site became the centre of the surrounding Lion's Hamlet, with museums and visitor facilities.
The structure commemorates the Allied victory at Waterloo and the wounding of William, Prince of Orange, during the battle. The lion was designed as a symbol of victory and power. It is therefore both a battlefield memorial and a carefully staged landscape monument, not a surviving natural hill.