Competitions are usually only open to women, who must race in heels that are at least 7cm high and no more than 1.5cm wide at the base.

BBC: High-heel racing for a cause

The tower, on East 22nd St. between Broadway and Park Avenue South, would be only 50 feet wide at the base but would expand like a slender champagne flute and be wider at the top, a rendering reviewed by The Wall Street Journal shows.

WSJ: For Developer, 3 Could Be Charm

Professor Garvey envisages a cone-like structure stretching 50 meters wide at the top to around 80 meters across at the base.

CNN: Where to store wind-powered energy? Under water!