Unlike the WW1 battlefields we visited in September, where the battles lasted for months over areas covering 100 to 500 square miles, Waterloo, which we saw on the last day of our trip, happened on one day, June 18, 1815. Though it was only one day, it was bloody, with 45-50,000 men killed or wounded, twice the toll of Antietam, the worst single day of America's Civil War.
Today, it is peaceful. But for the occasional monument and the two fortified farms on the flanks that still exist, Le Haye Sainte (privately owned) and Hougomont (open to the public), it is mostly open farm land (see this panorama from Wikipedia).
The very well done museum is underground and behind the main English/Dutch battle line. And then there is the Lion's Mound, the artificial hill, located at the center of the British position, constructed at the order of King William I of the Netherlands between 1820 and 1826. It rises 141 feet above the surrounding surface, with 226 steps to climb to the top. Unfortunately, its construction caused the topography to be dramatically changed, a change the Duke of Wellington found most distressing when he returned in 1828.
We did make the trek up and down the Lion's Mound.