Officials cut the red ribbon.
The city of Milan, next host for the World Expo, started its "showcase week" at the Italy Pavilion June 16.
The city's Head Councilor for Culture, Massimiliano Finazzer Flory, said the World Expo 2015 Milan would be "very different" from Shanghai's.
"The World Expo 2010 Shanghai is a great inspiration for the city of Milan, yet our plan is quite different," he said.
Flory said the master plan for Expo Milan, with the theme "Feeding the Planet, Energy for Life," had been confirmed.
The site is just a few kilometers from the center of Milan and includes a large global construction in the form of a greenhouse.
In Milan in 2015, participants will be designated a space in the globe. Flory said all participants would be welcome to bring seeds from their hometowns to plant in the globe.
China has confirmed its participation in World Expo Milan - the first country to do so.
Flory was at the Expo site yesterday to open Milan Week, with the theme "Milan, Creative City."
The city has been Shanghai's sister city since 1979.
The week will be celebrated with a bumper display of arts, design, cuisine, fashion, technology and architecture.
A different Milanese chef will be featured every day until June 23 in a cooking show in the pavilion from 10:30-11:30am.
Staff members will pick two to three visitors in the pavilion before the show starts. They will get to taste the end results.
Three forums, "Testimonials in Creativity," will also be held in the pavilion.
They will feature arts, design and information technology innovations and be presented by Milanese experts.
A collaboration between the Piccolo Theater and the Shanghai Theater Academy for the classic drama "Servant of Two Masters" will be Milan Week's official curtain-closer.