This one is completely new to me. Fascinating.
However, is the staircase really that amazing, or could a well-trained carpenter/building engineer make it? I mean, look at the pyramids, which were constructed so long ago, that they were about as old* to the ancient Romans as ancient Rome is to us now.
* The Great Pyramid was finished in ~2500 BC, and the Parthenon was finished in !430 BC ---> 2100 years. Ancient Rome as we generally think about it (Julius Caesar, Augustus Caesar, Mark Antony, and Cleopatra) is ~100 BC to 0AD ---> 2100 years.