The Millennium Dome is a dome-shaped multi-purpose building that was first installed in Zaragoza during its 2008 International Exhibition "Exposition Internacional de Zaragoza (2008)"). It was later acquired by the Valladolid City Council and installed in that city in the Plaza del Milenio. It opened in 2011.

The Millennium Dome, which gives its name to the Millennium Square, was brought from Expo Zaragoza 2008 "Zaragoza International Exhibition (2008)"), where it was part of the SED Pavilion. Located in Valladolid, it opened to the public in May 2011. It is part of a pilot project in Spain that seeks to experiment with a new city model that combats climate change.[1]​.

It is located in the Plaza del Milenio, next to the Pisuerga River, crossing the Isabel la Católica Bridge in the direction from the city center to the outskirts. The transfer and assembly operation cost 16 million euros, a fact that was criticized. His supposedly extravagant design, with colors and a dome shape, was also criticized, which breaks with all the harmony of the city's buildings.[2]​ With his work it could be said that a "Guggenheim effect" was pursued in the city.[3]​.

The Millennium dome, which covers the pavilion, has an area of ​​almost 1,700 square meters, while the planned capacity is set at 1,250 people seated or 2,500 standing. It also has underground parking for 402 vehicles, a bike path, a restaurant, a children's playground, water games and a mini adventure park.

Currently, all types of social and cultural activities are taking place, such as concerts, conferences, exhibitions, samples, advertising and sporting events...

It is covered with a material, called EFTE, crystalline like glass, and resistant, durable and flexible like plastic. And, unlike these two highly polluting elements, it is light, captures 90% of sunlight and emits only 80%, so it achieves natural lighting and cooling, generating most of the heating and air conditioning to acclimatize an area of ​​more than 1,500 square meters, except for a few days a year. This cooling is possible thanks to its three layers. One of them is covered with a special paint that incorporates aluminum microparticles that reflect solar heat.