It's a bunch of crap. I've written on the site and it's single director, Mr. Michael Tellinger, before, so I'll paste all that here. It's a little messy and sarcastic, but the main points are there.

TL;DR The main "researcher" at the site is Michael Tellinger, a recording artist with a pharmacy degree, who has spent very little time working there. He boasts that he's friends with people who attribute everything to aliens. He claims that Adam's Calendar is special for aligning with stars, when tracking star alignments is one of the most basic, earliest evidenced human ritual activities. His given dates for its occupation are outrageously inconsistent and do not use any established methods. He provides no evidence for this idea of a "mother culture," and claims connections between drastically different cultures separated by 6000 years. This also assume that elements of these cultures would be visible 25,000 years ago before millenia of cultural evolution and migration, when cultures that inhabit the same land 2000 years apart are often barely recognizable. Tellinger also accuses dissenters of robbing Africans of their heritage when he himself insists it was alien-inspired Eruasians who built the whole thing. But really in the end, it's Tellinger's complete lack of evidence that he's willing to show people. If you want people to even consider believing you, at least show them some photos of the artifacts you've found.

To begin: Who is Mr. Tellinger?

Good question. Most archaeologists would ask the same thing. Tellinger earned a degree in pharmacy, and then spent the 80s and 90s as a stage musical actor, film technician, and musician (he's released at least 13 CDs). The only place that calls him a "international authority on the origins of humankind " is his own site. But wait! Tellinger is also proud to be the compatriot of several "celebrities" on his "About Us" page. Let's look at them:

Graham Hancock (B.A. in sociology) is a racist hack journalist who believes all cultures came from one ancient unified culture. Robert Temple (B.A. in Oriental studies) promotes that an African tribe is in regular contact with aliens from the Sirius star system. David Wilcock is a New Age kook and Ancient Aliens star whose book on the 2012 prophecies discuss "DNA transformation, consciousness science, wormholes, stargate travel, sacred geometry, ancient conspiracies, multidimensional time, the Maya calendar, and a stunning new model of galactic energy fields triggering mental, biological, and spiritual evolution." Bob Dean, Kerry Cassidy, and Dr. Seven Greer are UFO-logists who insist governments are hiding information. Stanton Friedman (PhD) is a researcher who insists Roswell was really Aliens and that SETI is a waste of time. Semir Osmanagic, a publicist whose "research" on ancient "pyramids" in Bosnia is a cash cow for himself and the state. Couple this with an intense animosity towards every other archaeologist on the planet, "the brotherhood of conventional Archaeology, Paleontology and Anthropology," and you get an idea of who he is.

The Stone Circles

Tellinger's flaghsip theory describes a group of "First People" that lived 200,000 years ago in South Africa. In his own words:

Scholars have told us that the first civilisation on Earth emerged in a land called Sumer some 6000 years ago. The persistent research by South Africans Michael Tellinger, Johan Heine and a team of leading scientists, over an extend seven-year period, has resulted in astonishing new archaeological and scientific discoveries. It shows that the Sumerians and even the Egyptians inherited all their knowledge from an earlier advanced civilisation that lived at the southern tip of Africa more than 200,000 years ago… mining gold.

This makes me laugh. We begin with the cheapest of cheap strawman shots you'll see on every pseudo-archaeology blog ("Scholars have told us...). No archaeologist is arguing that. Nobody's even dividing "civilization" from its barbaric cousins any more. This idea of "civilization" springing out of the desert with uncertain antecedents is the product of simplified public school world history books from the 70s. Apparently that was Tellinger's last contact with archaeology.

"An extended seven-year period." Oh..oh my... seven YEARS you say?!?! By golly, that puts my recent nine-year project to shame. And what does that mean for the artifacts from earlier projects I've been looking at? Some of those come from excavations in 1958. Those 67 years of research can't compete. And I guess I'll discard those old travelouges from Charles Weiner that documented the site in 1880. Why study for 135 years when you can only do 7?!?

"The Sumerians and even the Egyptians..." It's funny that two civs, that appeared so different, with unique religions and art and language and scripts and architecture and sciences and technologies, should have gotten everything they knew from the same place and made no developments of their own. Wonder how that worked. And I had no idea that because someone predated you on the opposite side of a landmass, you by default inherited their culture.

"Astounding new archaeological and scientific discoveries" What are these archaeological discovers? Some stone circles in South Africa. Some call them cattle corrals. He calls them 250,000 year old structures. Unfortunately, his site provides no reason why we should believe his beyond "they look different." There's been no excavation and it's literally a bunch of stone circles, one of which is "special" for having no doors. Ever heard of 3 dimensions? You can also draw circles and triangles on top of them which is special I guess.

This is one of the theories so..."odd" that I haven't been able to find any actually good research on any of it. That's not because we're scared to engage with the powerful academic force of Michael Tellinger. It's because Telllinger's evidences are so obviously corrals and houses that it's nor worth anyone's energy to tell him they're not. Any archaeologist who looks at those structures sees literally nothing special. It's like if you've only ever seen blue Gatorade and I try to sell red Gatorade to you as a miracle elixir- obviously it's not the same as your Gatorade, it's red!

No legitimate dating methods have been used at the site, which they claim to be between 25,000 and 260,000 years old. An anonymous archaeoastronomer said that, based on old positions of the stars, some stones at Adam's Calendar line up with Orion's Belt from 75,000 years ago. This is not how you do archaeoastronomy. It is notoriously impercise, subject to, and prone to, confirmation bias. There's thousands of stars, of course something lines up. We also cannot treat it as some enormously advanced science to line up stones with stars- people across the globe have been doing it for thousands of years. Another date of 160,000 is based on the erosion of stone which has broken off of erect ones- I have no clue where they got the idea that stone weathering is a consistent process with a defined rate. I have yet to find a justification for the 260,000 year date.

Other Fun Statements

Apparently, there are "well over ten million" stone ruins in the mountains of southern Africa. I can't find a good number for the area that covers. But let's say it's the size of South Africa. This implies 8.19 sites per km2, or one site every .12 km2. That's smaller than the parking lot for the Tennessee Titans.

Evidence for "the Sumerians, Egyptians, Phoenicians, Romans, Greeks, Arabs, Dogon, Dravidians, and even the Incas" have been found in these southern African ruins. Odd that 100,000 years of human history should not be present at the site when the record suddenly picks up again 6000 years ago.

This is the real topper though:

Please note that while our newly published official history books by WITS University scholars (March 2015) claim that these were build by the Bakoni people - there is no scientific evidence for these claims whatsoever, but is pure speculation by scholars with inadequate knowledge and information. While the Bakoni people may have occupied these structures in the past 300 years or so, they did not consctruct them. The origins of the ruins are far more mysterious and are connected to the origins of humankind and the activity of the Anuna gods or Anunnaki, on planet Earth, as outlined in great detail in the Sumerian clay tablets. The continued rejection of ancient African knowledge by our Euro-centric academia, continues to rob the people of Africa of their true heritage and all of huimanity of our true origins.

Because when we deny the statements of an African University based on African researchers which attribute things to African cultures based on interviews with African people, and instead attribute them to a mythical race based on ancient writings from the archetypical Eurasian "mother culture," we're being so Eurocentric. Those Africans couldn't have built those structures, they're much too advanced for them. Stars and stuff man... you've gotta be real special to see them.