OverThere: The foundations of what will be the world's tallest building have been laid at a cost of $15m (€11.5m). However, mystery still surrounds just how high the $870m (€674m) Burj Dubai building in Dubai will be.

Currently, the title of world's tallest building is held by Taiwan's Taipei 101 - a vertigo-inducing 508 meters tall. But the developers of Burj Dubai, Emaar Properties PJSC of Dubai, suggest their building will be over 700 meters - almost half as tall again as Taipei 101. To put this in perspective, Liberty Hall in Dublin at 58 metres tall will be at least 12 times smaller than Burj Dubai.

Designed by Skidmore, Owings and Merrill (SOM), Burj Dubai's design is derived from the six-petal desert flower. The tower is composed of three elements around a central core. As the tower rises, setbacks occur at each element in an upward spiralling pattern, decreasing the building's mass as it reaches upward. The central core emerges at the top and is sculpted into a spire. The South Korea-based Samsung Corporation is due to start building the tower on April 15th with a completion date late 2009.