Towers in Peru called solar observatory - Los Angeles Times

Towers in Peru called solar observatory - Los Angeles Times: "'Unlike all the other sites, however, [Chankillo] contains alignments that cover the entire solar year,' said coauthor Ivan Ghezzi, who was a graduate student at Yale University when he did the work but is now archeological director of the National Culture Institute in Lima.

In effect, it is the oldest 'full-service observatory' in the Western Hemisphere."

Seriously cool and it took a lot of careful observation and mathematics to design and build something like this. It's one of those things you could actually do in you backyard on a small scale.