Built by Napoleon Lebrun & Sons in 1909, this clocktower landmark was the world’s tallest building until 1913. Its transformation from iconic structure to five-star hotel has brought with it only more reasons to visit, including, first and foremost, the on-site spa—a 39th-floor escape offering build-your-own treatments and a selection of enhancements. Other incentives are the restaurant Clocktower, where chef Jason Atherton delivers Michelin-starred dining by way of updated tavern classics and modern British fare, and the Lobby Bar, which serves signature libations alongside expansive views of Madison Square Park. Once room-bound, it’s easy to stay a while thanks to luxurious details like plush linen sofas, specially programmed iPads, and customized mini-bars.