Underground Valletta
After the Great Siege of 1565, the Knights learned from their travails. In building their grand fortress of Valletta, a labyrinth of tunnels was dug beneath the city so that in the event of future attacks, they could be used for troop movement. They also performed more practical functions, including drainage and storage for both grain and water. More than 1,000 cisterns were buried underground, and the bulk of the city's nonpotable water came from these. Centuries later, as World War II rained bombs down on the city, these cisterns and reservoirs were expanded into a series of shelters---you can still see the graffiti from bored citizens on their walls. For many years, these depths were off-limits (many of the tunnels still are and have been turned into private basements), but hour-long tours now guide groups around a small section. Tickets are available from the MUŻA ticket office or online. Tours are hourly between 10 am and 1 pm, with an extra 2 pm tour at weekends; closed-toe shoes are mandatory.