Location Stationsplein - near the large round water object

Seven times seven is? Correct: forty-nine. The big eye-catcher of this square is not the square itself, but the white bulbous roof. The pill strip, the bubble wrap, the egg carton, give it a name, everyone recognizes it these days. But what about that calculation: seven times seven? Just look around: how many pillars do you count? And then look up: how many bulbs do you count? I’ll tell what the diameter is of each of those spheres: it is seven meters. The amount of pillars times the diameter of the spheres = the number of spheres. 49.

Those spheres are actually balloons made of a special foil, developed in space technology. Bulbs of hard plastic or glass would be too heavy to make such a large, light roof. No dirt such as bird droppings and dust sticks to it. These light large balloons are filled with air. And the air pressure is maintained with small electric motors. This needs occasional maintenance. You would think that they would have a high-tech maintenance plan for such a high-tech roof. But that's… not quite right. Right on top of the large chic white entrance of Hoog Catharijne is a ladder just behind the edge of the facade. A maintenance engineer can put this ladder upright against the edge of the white bulb roof, secure himself with a lifeline and then climb up for maintenance on the installations in the roof. Why make it technically difficult when it can be done in a simple way?