125 years

Time it would take for a totally neglected wood-frame house to fall to the ground, according to Alan Weisman, author of the 2007 best seller The World Without Us. Watch the hypothetical structure's full 500-year demise in "Your House Without You," a companion animated video to his book. Weisman's what-if scenario has become part of the ongoing debate about what should happen to the homes in boomburgs/boomburbs that sit abandoned or were never finished in the first place. Let nature run its course, extremists say. New Urbanists take a more proactive view, arguing that there are ways to revitalize these 21st-century ghost towns.

Essential information: Read "10 Questions for . . . Marianne Cusato" for more details on New Urbanism.