H&M is putting one of the biggest billboards in New York City to promote its upcoming spring line. By this evening, the 15,200-square-foot ad of a woman wearing an H&M linen suit will appear on the city's oldest remaining skyscraper, the Flatiron Building. The giant poster will remain on the historical building for only a month as, by law, all billboards must be taken down after the renovation of a landmarked construction is complete and the scaffolding comes down.

 "It's great to take a landmark building and make it our own," H&M ad manager Steve Lubomski told New York Daily. "It's a desirable area with a lot of great shopping, plus there's not a lot of clutter."

And though the price was not disclosed, Lubomski said the size and prime location of the ad made it the most expensive billboard the Swedish retailer, who currently operates around 945 stores in 18 countries, paid for anywhere in the world.

Meanwhile, Hennes & Mauritz is launching its new Knightbridge store in London with a party that will feature a host of celebrities, including Saffron Aldridge, Jasmine Guinness, Liberty Ross, Lisa Butcher, Daisy and Poppy de Villeneuve, Iris Palmer and Natasha Law.