The site gave the brief before anyone drew anything: an open slope above the Tagus, wind off the water, and Lisbon sitting on the far bank in full view. Anything built there had to hold its own against that horizon without competing with it.
The canopy is a run of close-set timber over a raised deck, carried on a steel frame that also takes the weight of the rigging. It reads as shelter from below and as structure from the side. In daylight the slats drop a moving grid across the deck; after dark the frame disappears and only the load it carries is visible.