Tomb of the Sunken Skulls
http://www.ancientworldreview.com/2015/10/the-tomb-of-sunken-skulls-in-sweden.html
http://www.ancient-origins.net/unexplained-phenomena/tomb-sunken-skulls-sweden-sheds-light-prehistoric-inhabitants-002361
A Buried Ferrari
http://www.footmanjames.co.uk/blog/how-a-ferrari-ended-up-underground
https://jalopnik.com/5933077/we-solved-the-mystery-of-how-a-ferrari-ended-up-buried-in-someones-yard

Secret Bomb Shelters
https://www.nbcbayarea.com/news/local/Underground-Vaults-Bomb-Shelters-Delay-Soccer-Stadium-Opening-218172841.html
https://www.sjearthquakes.com/post/2013/07/29/kavals-kickoff-explaining-new-stadium-delay

The Shell Grotto
https://www.treehugger.com/culture/mysterious-underground-shell-grotto-margate.html
https://en.wikipedia.org/wiki/Shell_Grotto,_Margate
An Underground Cinema
https://en.wikipedia.org/wiki/Catacombs_of_Paris
https://www.atlasobscura.com/places/catacombes-de-paris
http://www.firstshowing.net/2013/secret-cinema-club-underneath-paris-photos/

The Neanderthal Building
https://www.theguardian.com/science/2016/may/25/neanderthals-built-mysterious-cave-structures-175000-years-ago
https://www.theverge.com/2016/5/25/11764204/neanderthal-cave-building-mystery-nature-study
https://www.theatlantic.com/science/archive/2016/05/the-astonishing-age-of-a-neanderthal-cave-construction-site/484070/

The Mount Owen Moa
http://strangesounds.org/2017/12/scary-archeology-the-mount-owen-moa.html
https://en.wikipedia.org/wiki/Moa
https://www.theepochtimes.com/uplift/the-frightening-discovery-of-the-mount-owen-claw_1113874.html
https://www.snopes.com/moa-troodon-claw-photo/

The Orvieto Pyramid
http://popular-archaeology.com/issue/fall-09012014/article/archaeologists-investigate-underground-structure-beneath-orvieto-italy
http://www.ancient-origins.net/news-history-archaeology/mysterious-ancient-etruscan-underground-pyramids-discovered-italy-002326

The Copper Scroll
https://en.wikipedia.org/wiki/Copper_Scroll
http://www.ancient-origins.net/ancient-places-asia/lost-treasure-copper-scroll-001457

The Tecaxic Calixtlahauca Head
https://en.wikipedia.org/wiki/Tecaxic-Calixtlahuaca_head
http://www.ancient-origins.net/artifacts-other-artifacts/tecaxic-calixtlahuaca-head-evidence-ancient-roman-transatlantic-voyages-021076