The Salar de Uyuni in Bolivia is the largest salt flat in the world, coming in at just over 4,000 square miles. Part of the flat has been unofficially designated as a train graveyard, housing tons of rusty, decayed locomotives.
The trains, many of which are now covered in graffiti, are mostly from Britain and date back to the 20th century. They decayed quickly, however, due to harsh salt winds. Visitors can now freely explore the odd attraction when visiting the remote salt flat.