The islands of Burano, Mazzorbo & Torcello in the Venice lagoon are very close to each other. Burano and Mazzorbo are linked by a bridge and Torcello is a short 5-10 minute boat ride..
Torcello is the oldest continually occupied region of Venice and was once the most populpus. Today it is very sparsely populated due to malaria. It has a population of 10 including a priest. You can guess that it was once much more populous due to it's fine Duomo (well worth visiting!).