Photo by Peter Korrak

For a hundred years or so, Vienna invested in coal/gas energy, but when the plant was decommissioned there were four large gasometers remaining.  The imposing structures sat idly, appearing in the James Bond movie, The Living Daylights and hosting rave parties.

Rather than tear them down, architects designed them to be converted into apartment style housing.  First, they gutted the structures.

Each gasometer was divided into several zones for living (apartments in the top), working (offices in the middle floors) and entertainment and shopping (shopping malls in the ground floors). The shopping mall levels in each gasometer are connected to the others by skybridges.

Additional features:
Over 70 restaurants/bars/cafes
A multiplex cinema with 12 screens
4200 person capacity events hall
Daycare center
The Vienna National Archive
11,000 square meters (118,403 sq ft) of office space
615 apartments
230-bed student dorm

Link with many cool photos.