Larry Page has his flying cars. Sergey Brin shall have an airship.

Brin, the Google co-founder, has secretly been building a massive airship inside of Hangar 2 at the NASA Ames Research Center, according to four people with knowledge of the project. It's unclear whether the craft, which looks like a zeppelin, is a hobby or something Brin hopes to turn into a business. "Sorry, I don't have anything to say about this topic right now," Brin wrote in an email.

The people familiar with the project said Brin has long been fascinated by airships. His interest in the crafts started when Brin would visit Ames, which is located next to Google parent Alphabet Inc.'s headquarters in Mountain View, California. In the 1930s, Ames was home to the USS Macon, a huge airship built by the U.S. Navy. About three years ago, Brin decided to build one of his own after ogling old photos of the Macon.