(from the inside) that is one of the most interesting/good looking hangars i have ever seen.
smt
Well spotted: those hangars are world heritage and the foundation of one of largest construction companies of Europ.
The structure is designed like a mushroom with as only support the central part. Nowhere in the roofsection the concrete is thicker than 10 cm (4 inch). All concrete was poured manually (wheelborrows)
I have briefly known the designer/ maker, who was quite excentric at the end of his life (I automated for him a 6 m high bronze "Prancing Horse" (a personal gift of a that Italian car maker he raced and won for) so the horse would look at the room (in the castle) where he was. How strange he could be to others, how normal he was with me: sharing pictures and anecdotes about the construction, how everybody refused to remove scaffolding after the concrete had hardened (fear of collapse) He did that alone and claimed being 3 days being drunk on champagne afterwards.
On the other hand : the "small" job (1 hour) of greasing the ring wheel of the horse I always did on saturday or sunday because he would keep me the day. He would fly back from the South of France "to supervise"
The round hangars (each shelters about 40-60 aiplanes) proved valid and time resistant yet no big commercial succes, there is a small one at Antwerp and a (farm equipment housing) one in the North of France. They required minimal construction materials yet maximum labor.
He also had an ugly appartement building (very little to no visitors allowed) in a "lesser part" of Brussels with several floors of racing cars (le Mans , Formula 1 etc) all ready to start. He raced them under a fake name "so his familiy would know him racing". Let's say he (nor his family) were poor.
Normally I refuse fees on the job, paying the invoice on time is more than enough. However everytime I worked for him , I got "drink money" of about 20000 fr (in 1994-1997) , that is about 1000-1500 USD now. Always the same words: "Don't tell your boss!"
As of now: Hangar 1 at EBGB is in restauration: at the outside (ground level) there is a concrete ring / steel rail on which the gliding doors rest. These are only guided at the top. That ring / steel rail needed work and also some minimalist concrete repair at the "edge" of the mushroom.