when was the last time a city got completely destroyed? and not repopulated.  Pompey?
Well, when Atttila the Hun invaded Italy, he razed the coast city Aquileia. The survivors never returned to the city and started to live at the sea isles and lagoons near the coast. So, Venice was set. The name "Venice" come from a Latin phrase that can be translated as "Are you here too [hiding from the huns]?"
Managua, Nicaragua was destroyed in the 1972 earthquake.  My ex-wife said that the damaged buildings were abandoned.  This article states that only recently have these properties begun restoration.

http://library.thinkquest.org/17749/earthquake.html