For those of us lucky enough to live through the golden age of animation (good ol' 80's cartoons), who got to see first hand the Mysterious Cities of Gold, it may be of interest that there is a Feature-length movie slated for production sometime in the very near future. Unfortunately, most of the information I found is in Japanese, so unless you can read that language, details are sketchy - even translating the page is a little hard, having the title "cities of gold" translated as "gold town" using the software provided. But I'm going to guess that it's an adaption of the original tv-series.

Wiki article
Japanese Official site (in Japanese)
Official Page, (poor) English translation

And for nostalgia - the Intro theme of the original tv-series, plus the Shortened version of the theme.

For those that don't know the story, it is a mix of ancient South-American history, fantasy, and science fiction. It revolves around three children, Esteban - an orphan who has the power to control the sun, Zia - an Incan girl with a mysterious past, and Tao - the last surviving member of the Ancient Hiva people (a highly advanced, now-dead civilisation). Together, they have been unavoidably set on a path to find one of the seven mysterious cities of gold. Chased by the Spanish (Captain Gaspar, Commander Gomez) who want the gold for themselves, and aided by Mendoza, an experienced navigator who rescued Esteban from drowning when he was a baby, but whose loyalties are always in question, and his mercenary friends Sancho and Pedro (dim-witted, but ultimately good natured), they go through trials and troubles over the course of the series.

Needless to say, I highly recommend it and hope the movie lives up to my already high expectations

Ha ha! I loved Cities of Gold. I've yet to meet anyone who saw the last episodes and found out how it ended - there were loads of episodes weren't there?

Didn't it end with them flying off in a big condor shaped machine?

I've seen all the episodes (39 in total). It's on DVD (hasn't come out in Australia yet, but that hasn't stopped me, lol). I don't want to spoil the ending for people though - my PM box is always available if people want to know what happened. Chances are the movie will be similar.

I used to sing to the theme song when I was younger. He-man and dino riders are my favourite still and ........count duckula.