Indeed it i large. So were the pyramids of Egypt. It is my belief that it was not slave labor that built the great structures but rather the Goliath type people of that day. This would take us back to pre flood era of Noah. And even before back to the days of Enoch and Genesis 6. Some folks believe that fallen angels mated with human women and produced the goliaths and oversized giants who could have made such masterpieces and wonders of our world. Thanks @kus-knee as it is intriguing.