In 1974 the roof of the olympic stadium in Munich, Germany was completed. It is a steel rope construction. Instead of using a liner, the designer Frei-Otto choose acrylic sheet for the semi transparent cover.
The whole idea might have been based on the Montreal Biosphère by Buckminster Fuller. That dome was build in 1967. The building originally formed an enclosed structure of steel and acrylic cells.
Unlike float glass acrylic panels can be used as structural elements in architecture. Acrylic is used to withstand high loads and has proven to retain its stability over several decennia.