The era between the world wars brought a building boom to the city, leaving it with many modern and especially functionalist buildings, the most celebrated one being Villa Tugendhat, designed by architect Ludwig Mies van der Rohe in the 1920s for the wealthy family of Fritz Tugendhat, and finished in 1930. It was designated a World Heritage Site by UNESCO in 2001. Another renowned architect who significantly shaped Brno was Arnošt Wiesner. Other functionalist buildings include Avion Hotel and Morava Palace. The Brno Exhibition Centre is the city's premier attraction for international business visitors. Annually, over one million visitors attend over 40 professional trade fairs and business conferences held here.