Military bunkers were primarily built for protection from natural disasters and war attacks, then left abandoned for many years. But these days, developers are seeing the potential—and payoff—in renovating them for commercial use. Begin slideshow

1.Bahnhof Data Center YouTube/Bahnhof AB Location: Attinghausen, Sweden Made to protect soldiers during the 1950s, this Swiss Alps bunker is now used to protect data by digital encryption and storage company WISeKey. The high-tech bunker is one of only four used by the company throughout Switzerland.

2. Waikele Storage Park YouTube/KITV Location: Oahu, HI What was formerly the Waikele Gulch Bunkers is a popular storage facility called Waikele Storage Park. The 120 underground bunkers total about 400k SF, with one 4k SF warehouse priced at $300k. The entire park takes up about 1.2M SF.

3. Crown Wine Cellars Wikimedia/2009534406wu09 Location: Shouson Hill, Hong Kong Located about 15 yards within a hillside, this climate-controlled 1k SF bunker is home to over 25,000 high-end bottles of wine, now owned by Crown Wine Cellars. The bunker is one of eight built in the 1930s to help in the resistance against Japanese invaders. The bunkers were used as rock core storage until bought by Crown Worldwide in 2003.

4. Sammlung Boros Wikimedia/Nicor Location: Berlin The Nazis first conditioned this 1942 bunker to be an air-raid shelter for civilians. It took a cultural turn as a club in the '90s, and was purchased in 2001 by real estate investor Nippon Development Corporation GmbH. Two years later, Christian Boros purchased and renovated it into a 32k SF exhibition space to showcase his private collection of contemporary art.