The roof is definitely closed for security reasons since april 2010.

Inaugurated 14 July 1989, the Grande Arche, built on the historical axis of Paris, was part of the policy of great works by President François Mitterand.
The roof was officially closed to the public in April 2010 following problems with the lifts.
The premises are to be converted into offices.

Ascend 110 metres in the panoramic glass lifts, unique in the world. From the panoramic viewpoint, visitors can admire the east of Paris including the Stade de France and Mont Valérien and also the Seine, the Sacré Coeur, the Arc de Triomphe (on the historical axis), and the Eiffel Tower - Montparnasse Tower axis, not forgetting the business district.

The roof of the Grande Arche hosted the Musée de l'informatique (opened in April 2001), the Musée de jeu video (opened April 14 2010) and a gastronomic restaurant.