Centennial Bridge towering above Soberanía National Park, Panama

© David Tipling/Universal Images Group via Getty Image

Celebrating Panama's independence. Centennial Bridge

This striking suspension bridge in a rainforest can be found in Panama, which celebrates its independence day today. However, on this strategic, ocean-straddling strip of land, independence is complicated. When Panama broke loose from Spain on this day in 1821, it became part of Colombia until November 1903 when, backed by the US, it became fully independent, just before the Panama Canal was built. (The Centennial Bridge over the canal, shown here, was finished in 2003 to commemorate 100 years since that event.) The US spearheaded building the international waterway, and controlled it until 31 December 1999, when Panamanians finally assumed full command of the canal, one of Panama's chief sources of revenue.