Straddling the United States and Canadian border, 340 miles (547km) northwest of New York City, the Niagara Falls are one of the most popular natural attractions in the country, attracting about 13 million tourists a year. The Niagara River has been flowing for about 12,000 years but the eroded escarpment over which the falls flow today is much older, having been formed during the ice age. The river plunges over a cliff of dolostone and shale to make it the second largest waterfall on earth, after the Victoria Falls in southern Africa. The mighty torrent is best appreciated from a spray-filled 'Maid of the Mist' boat tour, but there are many different tours and tickets available. The falls have attracted daredevils over the years, who have gone down them in various contraptions. The most famous stunt was done by the Frenchman Jean François Gravelot, who crossed the Niagara Falls on a tightrope in 1859. Traditionally a honeymoon destination, the area around the Falls has been built up into a major tourist area, with attractions like Ripley's Believe it or Not Museum, and cheap eateries and chain restaurants.