The Mysterious Cities of Gold - S4E8 - Ophir

Looks a bit like Atlantica from Disney's Little Mermaid.

As our heroes are about to be killed by the olmec Mendoza hits a tile that shoots out a pillar pushing the olmec into the waters. According to the documentary it's the Victoria Falls (which I thought, but got stuck by the name Niagara Falls which I know is between Canada and the US). Ambrosius and the others start up the city of gold and search for the philosopher's stone. The heroes add their medallions as well and they notice that Ambrosius have gotten his medallions out which their's usually don't as they seem to be locked in place, almost as if they gather data from the cities themselves. 

During the fight with the olmec Mendoza was shoot in his hand and as they enter the factory part they see it creating diamonds (which would explain the Queen of Sheba's riches), but a laser seems to fire into it. Closer look into it reveal a DNA-helix which they don't know what it is. This cuts to Tao and Nostradamus in France discussing astrology and such as well this special staircase that I assume is formed like a helix and supposedly created by da Vinci. 

Zia drops one that Mendoza catches, and as he does it lights up and disappears, but at the same time his wounds are healed. Healing crystals. Meanwhile Ambrosius have found the room with the stone, but it flies in the middle of it, hoovering over a gigantic diamond and several rocks flying beside it. Leguerra is forced to get to it, but Esteban jumps in to get it before them. Ambrosius send the other Olmec and Gaspard to deal with the others and tries to follow, but the rocks start turning in circles. The others are attacked by the villains and Mendoza uses one of the laser things to keep them at bay so that Zia can run to Esteban and get to the middle of the room first. Mendoza have to save Pedro from being crushed by the diamond press, but it seems to shut down the whole city and below the waterfall the first Olmec washes ashore.

As mentioned the documentary was on the Victoria Falls and a bit about rainbows. Apparently the inspiration for the city was a local tribes deity of a fish god that protects them. Which is interesting since the city was built 10 000 years ago and never shown I thought. But then, how could the Queen of Sheba have the philosopher's stone? Or the treasures for that matter without having the medallions herself? Or was she the one that had the double medallions that Ambrosius now possess?