This Way In

 

"The Sacred Well of Garlo is an intriguing archaeological site located near the village of Garlo in Pernik District, Bulgaria. Constructed between the 12th and 11th centuries BC, this ancient structure is nestled in a small valley rich with natural springs. The well's design and function bear striking similarities to sacred wells found within the remains of the Nuragic Civilization (1600–730 BC) on the island of Sardinia, Italy."

Also, it is clearly the entrance to an underdark dungeon of immense scope. It's obvious.

Westhead

This is Westhead, on the western side of the River Norflowd as it exits Roddenberry Gorge. There was originally a matching head carved into the cliffs on the eastern side of the river as well, but it has weathered away to the point of being virtually indistinguishable from a natural mountain-side.

It is one of the most southerly of the great stone heads carved into the hills of the Headland. There is only one further south than this, at Southead.