The construction of the Panama Canal remains one of the most formidable feats of engineering in human history and one that dramatically changed shipping. Appalling working conditions and accidents hindered its progress and saw thousands of workers perish, however. But after decades of strife and a change from French hands to American, the project - which started in 1880 - finally saw Pacific and Atlantic Oceans meet in 1914. The thin, 77km long channel is held in check by three enormous sets of locks. Around 14,500 ships now pass through it annually.