This magnificent room was made in the 1500's to hold 500 government officials, thus it name.
The large meeting room was suggested by Savonarola, the Dominican prior of San Marco.
The room was a great engineering effort by Polliuaolo, with its enormous size and high ceiling,
both of which were adjusted from a much smaller area.

Originally dereft of decoraitons, frescoes were planned to be done by Michelangelo on one side, ("Battle of Casina"),
and by Leonardo da Vinci on the other side ("Battle of Anghiari").
Michelangelo's plan only got as far as large scale sketches
which became quite famous. There is evidence that Leonardo began his frescoes, but that they were
partially destroyed by either his experimental painting process, or weather realted issues.
Ongoing efforst are attempting to find evidence of this work beneath the current frescoes done by Giorgio Vasari in ca 1540's

The Salon de Cinquecento was one of the settings in Dan Brown's "Inferno",
where a major character fell through the ceiling.