The architecture of the tower was by Leonor Janeiro, Nick Jacobs and SOM. The steel structure, representing the sail of a caravel, was assembled by engineering company Martifer.
The tower was built in 1998 for the Expo 98 World's Fair. At the 120 m/394 ft-level, there was an observation deck and, just below it, a luxury panoramic restaurant. At the base of the tower was a three-storey building that served as the European Union Pavilion during the expo.
Both the observation deck and the restaurant were closed in October 2004. While they were open, the tower was the tallest structure in Portugal open to the public (excluding bridges).
The base 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. In 2006 the tower was climbed by Alain Robert, a solo urban climber. He was sponsored by Optimus, a Portuguese mobile phone company, that used the climb as part of a marketing campaign for a recently released product.