I can count a handful of US building codes the Ribbon Staircase violates....but since it is oversees in Prague, I think I'll let it slide...
Designed by HSH architects, the ribbon staircase is constructed of 10 mm thick sheet metal. Don't let the airy/light appearance fool you, the staircase is anchored well to the wall with external side joist brackets and each bracket is constructed as a rigid frame.
The higher steps bear mainly drawing forces, while pressure is transmitted through the lower steps.
Strong as it may be.... I'm still going to look before I step.