The Louvre in Paris -- the world's most visited museum -- reopens on Monday. It's been closed for nearly four months, with an economic loss estimated at over 40 million euros. Authorities say coronavirus restrictions, however, are still in place and parts of the complex remain closed to visitors. People will have to wear masks, and follow a guided path through the museum. Positions have been marked out in front of the MonaLisa to ensure social distancing. The Louvre has upped its virtual presence as well during the lockdown.