Oldest structure in the world??

I honestly don't know what to make of this one. I am looking for an academic viewpoint of this groundbreaking artifact.

Two South African men, Johan Heine and Michael Tellinger, have released a book about a supposedly ground-breaking find - Adam's Calendar.

Tellinger believes that the site [of the calendar] ties up with an era when human beings first started painting in caves and started their migration into Europe and Asia from Africa between 60 000 and 70 000 years ago.

The two explorers also found that two of the central rocks work as a calendar, with a tall rock casting a shadow on a shorter, flat rock. The shadow moves across the rock in exactly one year

The authors believe that this monument dates as far back as 75 000 years, making it the oldest man-made structure.

Here's where it gets dicey. Tellinger is also the author of a far-out (I say far-fetched) book called Slave Species of God.

Let's say it's a new take on human origins, one that involves little green men and their quest for gold.

And I thought the reptilian creatures living in the center of the earth was an out there concept!

Again, let me say ... I don't know what to make of this discovery. So don't make it an ice-breaker topic at parties just yet!