Picture of the Day 7/31: What is this?

If you know what this is and where it's located, you could win a prize in the CNET Road Trip Picture of the Day challenge.

(Credit: Daniel Terdiman/CNET)

Update (Saturday, 7:41 p.m. Pacific): The answer to today's challenge--which 77 people got--is the Eel Pond drawbridge in Woods Hole, Massachusetts, next to that town's community hall building. Congratulations to today's winner, and to everyone, please come back for Sunday's challenge.

This might look like an optical illusion at first sight, and maybe it is. Either way, if you know what this is and where it's located, you could win a prize in the CNET Road Trip Picture of the Day challenge.

If you have those answers, please e-mail them to me no later than 6 p.m. PDT Saturday (to daniel--dot--terdiman--at--cnet--dot--com, and PLEASE include "Picture of the Day" in the subject line). I'll choose a winner at random from among everyone who sends in both pieces of the correct answer. Please forgive me if you don't hear from me if you're not the winner. I get dozens of responses each day.

Also, I've turned off comments because some people have been posting the correct answers there. I hate to shut down discussion, but I want you to figure out the answer on your own.

One caveat: no individual can win more than two prizes. But at the end of the trip, I'll draw a name from among all the daily challenge winners and give out something a little more substantial.

On June 24, Geek Gestalt kicked off Road Trip 2010. After driving more than 18,000 miles in the Rocky Mountains, the Pacific Northwest, the Southwest, and the Southeast over the last four years, I'm looking for the best in technology, science, military, nature, aviation, and more throughout the American northeast. If you have a suggestion for someplace to visit, drop me a line. In the meantime, you can follow my journey on Twitter @GreeterDan and @RoadTrip and find the project on Facebook.