Atlas Obscura is one of the largest, most well-known and most impeccably awesome archives of amazing places, foods and experiences in the world.
Here is their list of places to see in Belgium! From a giant iron crystal magnified 165 million times you can climb inside, to a peeing Belgian icon and its many variants, to a collection of over 50 murals celebrating Brussels as "the birthplace of the comic strip", to a dreamlike carpet of bluebells draping over the forest floor each spring, Belgium is a pretty cool place with pretty cool places! How many of these awesome sites have you been to?
Note: Some of these you cannot visit or see anymore, which have been marked with (Permanently Closed). So therefore, if you haven't already seen them, I don't know if you'll ever be able to completely finish this list.
Note 2: This is as of May 27, 2024. Sorry future people, there will definitely be more that can't be added.