This 10 minute video details Jim Allen's hypothesis that Atlantis was located in Bolivia. IT goes quickly, so you may have to stop and start it often. The evidence is circumstantial. 1. There was definitely a very large civilisation in South America that left behind ruins, 2. Pre-Columbian travel between the old and new world really happened, and 3. that ancient South American civilisation bears a resemblance to the description of Atlantis in Plato's dialogues, but while 1 and 2 are established facts, 3 is an inference alone. The resemblance might well be coincidental. There may or may not be issues with the dating of these sites, I don't know, I haven't looked into it too carefully. The video is worth watching and, as always, I recommend you form your own opinions.