Map Mysteries – Latitude and Longitude

What is the feature located at each of these latitude and longitude coordinates?
Why is this feature important?
Is the feature natural or created by humans?
Why is the feature located where it is?

Latitude and Longitude:

29.98, 31.13
38, -123
43.09, -79.07
-33.85, 151.21
27.17, 78.04
19.84, -155.50
-17.925, 25.855
48.858, 2.294
51.47, 0