France will review the protection of cultural sites across the country and beef up security if needed, officials said on Monday as a manhunt was under way for the four people who staged an audacious daylight robbery at the Louvre museum. The thieves broke into the Louvre using a crane to smash an upstairs window, then stole priceless objects from an area that houses the French crown jewels before escaping on motorbikes. The theft, which several newspapers called "heist of the century", grabbed headlines globally. The museum, which shut after the robbery on Sunday morning, remained closed on Monday. The break-in raised awkward questions about security at the museum, which is home to art works such as the Mona Lisa...