Undoubtedly the most prestigious opera house in the world, its simple exterior gives little idea as to the magnificence that awaits within, as visitors to the opera house museum will see from a box. Built between 1776 and 1778, the six-tiered auditorium can seat up to 3 600. The opera season begins on 7 December each year, on Sant'Ambrogio's day). The elevation to the wings by Mario Botta has given the edifice a new outline.