Where is the head office of the agency that designed the Tour Triangle?
Tour Triangle:  Designed by the Swiss agency Herzog & de Meuron, it will take the shape of a 180 m tall glass pyramid with trapezoid base, wide from one side and narrow from another. Herzog &amp; de Meuron: Herzog & de Meuron Basel Ltd., or Herzog & de Meuron Architekten, BSA/SIA/ETH (HdM), is a Swiss architecture firm with its head office in Basel, Switzerland.
Basel, Switzerland