Up close with Google's mystery barge (pictures)

For several months, Google has been building a secret project atop a barge in San Francisco Bay. The ultimate purpose of the structure has been challenging to fathom. What is clear is that there's intense interest in the project, in part because of its hush-hush nature.

Update November 6 at 12:40 p.m. PT: In a newly issued statement, Google has finally acknowledged its connection to the project, as well as the speculation that had been building up: "Google Barge ... A floating data center? A wild party boat? A barge housing the last remaining dinosaur? Sadly, none of the above. Although it's still early days and things may change, we're exploring using the barge as an interactive space where people can learn about new technology."

The mystery Google barge and structure are seen with the brand-new eastern span of the Bay Bridge behind it.

There has been some skepticism that the mystery barge project could be a Google Glass retail or marketing center because the structure has very narrow windows.

The mystery structure is mostly covered in dark netting and scaffolding.

On the northeast corner of the structure, one of the shipping containers bends down from the second floor and hits the ground floor. Covered up by some sort of tarp, this is likely a main entryway.

A look at the north side of the structure, and the stairway going up from the ground floor, as well as several doors and a number of narrow windows.

A look at the roofline of the structure.

The mystery Google barge structure is seen with both the new eastern span of the Bay Bridge, and the now-retired span, which will soon be destroyed.

A single door leads to a small balcony on the north side of the structure.

The San Francisco mystery barge was built atop barge No. BAL0010. That's binary for 2. There are actually four barges related to the project. Two are in San Francisco -- BAL0001 and BAL0010 -- and one is in Portland, Maine (BAL0011). The fourth one, BAL0100, is unaccounted for.

A look, straight-on, at the eastern side of the structure.

It's hard to tell what's going on inside the structure, but from the water, you can see into the building's first floor.