El Dorado is a mythical Lost City of Gold said be located in the Jungles of Central/South America. It is frequently portrayed as being an Aztec or otherwise mesoamerican nation where gold was used to construct the city.
El Dorado was a colonial-Spanish myth created through misinterpretations of El Hombre Dorado ("The Golden Man") or El Rey Dorado ("The Golden King"). Indigenous central-American cultures did not utilize gold as a currency due to it having little practical worth outside of its usage as an artistic resource. Because of this it was used in cultural practices such as being used to paint religious figures in gold body-paint or tossing gold into water-bodies as a ritualistic tribute.
However, Spanish colonists didn't understand that the indigenous did not consider gold as a precious resource and rather decided that the reason they used it like this was because they had a massive stash of gold hidden away. Due to a combination of myth circulation and colonial propaganda, this story of a hidden indigenous gold-stash evolved to a lost city of gold called El Dorado hidden in the jungle. This myth lead to many explorers and colonists attempting to search and map the jungles to no avail and many indigenous peoples bartering, "information" of El Dorado for peace, often leading colonists to an early grave.
In the 4th Indiana Jones film, Indiana Jones and the Kingdom of the Crystal Skull (2008), El Dorado is the colonial name given to the lost kingdom of Akator. Akator here was an advanced nation created by the combined efforts of mesoamerican peoples and 13 inter-dimensional beings who left their crystal skeletons behind. In 1957, Akator would be discovered by Indiana Jones, his biological son Mutt Williams and his former lover-turned-wife Marion Ravenwood.
Appearances and allusions
In a letter sent to fellow S.E.A.-member Barnabas T. Bullion, S.E.A. president Jason Chandler mentions how he and Bullion had a, "little misadventure" in El Dorado. This adventure occurred prior to 1880 and was apparently the last time that Chandler and Bullion talked before Bullion contacting Chandler for help with his mining-operation. This letter can be found in the queue for Big Thunder Mountain Railroad in Walt Disney World's Magic Kingdom. El Dorado is also the namesake of the El Dorado Hotel in Rainbow Ridge. 
Around 2007-2008, Trader Sam was given a Crystal Skull tablet showing one of the skulls of Akator to promote Indiana Jones and the Kingdom of the Crystal Skull. This tablet however has since been removed due to the critical bombing of the film.
Miguel’s El Dorado Cantina
This is an Aztec themes restaurant in the village of the Lost River Delta which has El Dorado as its namesake and logo. In its backstory, the restaurant is run by a man named Miguel who came upon the Lost River Delta while searching in vain for the legendary city of gold. There is artwork of characters from the Pixar film Coco (2017) on the restaurant's exterior.
- Close Encounters with the Third Kind: The aliens of Akator look near identical to those found in this Steven Spielberg film and use a similar space-ship.
- E.T.: A carving of the aliens from the film E.T. appear in Akator as depicted in the film.
In Akator as seen in the film, there are gold carvings of the characters R2-D2 and C3PO from Star Wars, both of whom notably appear in Star Tours.
- The temple of Akator is not to be confused with the Temple of the Crystal Skull which is the mesoamerican setting for Indiana Jones Adventure: Temple of the Crystal Skull that also prominently features a crystal skull.