The tower was built in 1998 for the
Expo '98 World's Fair. At the base of the tower was a three-story building that served as the
European Union Pavilion during the Expo. While they were open, the tower was the
tallest structure in Portugal open to the public (excluding bridges). The base of the building was to be leased for office space after the closing of the Expo, but never found tenants. Instead, it was used for one-off events, like the world premiere of the new
Mini car in 2001. Both the observation deck and the restaurant were closed in October 2004. In 2006, the tower was climbed by
Alain Robert, a solo
urban climber, who was sponsored by
Optimus Telecommunications (a Portuguese mobile phone company) as part of a mobile marketing campaign. Parque Expo received permission to expand along the riverside in order to build a 20-floor, 178-room luxury hotel, a plan by Portuguese architect Nuno Leónidas. The base of the tower was demolished between July and September 2007, paving the way for the construction of the 5-star
Myriad hotel, which opened in 2012. In 2018, the panoramic restaurant
Fifty Seconds (by
Martín Berasategui) opened in the space that was previously the observation deck. Within a year, it received its first
Michelin star. ==Architecture==