The triangular plan is efficient (that's why it was used in Toronto's CN Tower, until recently the world's tallest freestanding structure)- "the vertical city is a powerful triumvirate of three ‘arms’ that meet at a central green spine running the full height of the tower. Wider at the base and tapering towards the top, the pyramidal form is elegant and slender in profile, and benefits from a highly efficient composition to achieve the maximum stability with the minimum structure, as well as the most effective distribution of space."
Green Tower in Moscow by Foster
