Designer Giorgio Armani greets Chinese actress Zhang Ziyi at the 40th Anniversary Dinner Reception in Milan, May 1st,2015.[Photo/Xinhua]

Italy's Giorgio Armani celebrated 40 years in fashion with a star-studded gala and opening of a museum dedicated to his designer business.

The 80-year old designer, known for his clean cut and elegant collections, was joined by celebrities such as Leonardo Di Caprio, Cate Blanchett, Hilary Swank and Tina Turner for the bash in Milan, headquarters to his fashion empire.

Nicknamed King Giorgio, the designer, who once worked as a window dresser, is known for being hands-on in creating one of the most recognised fashion brands in the world.

For the anniversary, Armani has converted a 1950s building that once stored cereals for a new exhibition dedicated of his designs.

The event took place ahead of the Friday opening of Milan Expo, of which Armani is special ambassador for fashion.

Officials are counting on some 20 million people visiting the six month exhibition of worldwide products and technologies.