One of the must sees in Panama has got to be the Panama Canal. The closest spot to Panama city are the Miraflores locks. It's auctually a really good museum as well. There is a theatre where you can watch a video about the canal. As you climb each floor you learn interesting facts like how the canal works and one thing I didn't know previously was that Panama made a second bigger canal to accommodate bigger ships. The top floor is the viewing area where you can look at the canal and if you come at the right times, you can see the ships going through the locks.