Ya know, I was googling about real world city of gold, just seeing if there was any lore out there to connect/draw on..and lookie what I found:
https://en.wikipedia.org/wiki/The_My...Cities_of_Gold
Anime, from the 80s. And seemed to be popular amongst people now in their 40-50s when they were kids. (See also Nadia: Secret of Blue Water)
Plot:
In1532(whatever year it is), a SharlayanSpanishorphan named KrilleEstebanjoins the WoL and crewMendoza, a navigator, and his associates Sancho and Pedro, in their search for one of the Seven Cities of Gold in the New World, hoping to find herhisfather. They are joined on their quest by Wuk LamutZia, a Turalian Incangirl, and ErenvilleTao, the last descendant of the sunken empire ofMuWhatever Solution 9 Is.
The series is a mix of ancient South American history, archaeology, and science fiction. During their journey, the travelers encounter the tribes of TuralMayas, Incas, and Olmecs. They discover many lost technological wonders ofthe Mu EmpireSolution 9, including a solar-powered ship (the Solaris) and The Golden Condor, a huge solar-powered ornithopter (mechanical bird), capable of traveling considerable distances under the sun's power alone. They are constantly pursued by antagonists, who are also in search of the Cities of Gold.
The Seven Cities of Gold were built by the Emperor ofMuSolution 9 out of fear that a global war would destroy all civilizations. Such a war actually broke out, destroying the Empires ofMuSolution 9 and Atlantis when they used the "Weapons of the Sun".The Seven Cities of Gold hold copies of books in their "Universal Libraries" as well as powerful artifacts, including the "Great Legacy", an Aether-rector (MAKO?)portable fusion reactor. Other elements of this technology turn up in unexpected places, like the Solaris on Erenville'sTao'shome island, Krille'sEsteban'sand Wuk Lamut'sZia'smedallions as keys to the Cities, and Erenville'sTao'sjar as an important piece of the Great Legacy.
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there's more...but I thought this might bring a laugh.