Google Science Fair

This week, the finalists of Google's grand student science competition, Google Science Fair, gathered at the company's Mountain View, Calif., headquarters.

Thousands of teenagers worldwide from more than 100 countries entered the second annual event, which aims to make easy for students around the world to pursue their interests in science and technology. The 15 global finalists -- with projects tackling everything from subsistence farming to treating methamphetamine addictions -- are at the Googlplex to present their projects to the judges.

This evening, three winners will be announced, with one from each age group 13-14, 15-16, and 17-18, and a grand prize winner.

Here, a directional signpost on the Google campus points the way to the 15 finalists' hometowns.