When buying tickets for the Atomium, you will get the chance to visit for free the ADAM Museum, situated between Brussels' Modernist Expo center and the Atomium. This atypical museum is a space dedicated to design from the 20th and 21st centuries and it is best known for its Plasticarium Collection, a permanent quirky exhibition of plastic design. This museum's creativity will definitely inspire you and the temporary exhibitions are always a nice surprise! There's also a kid-friendly section inside with information about recycling and facts about plastic.