For the word a week challenge- holes- I have chosen two holes made by nature in the south west (of the U.S.) the first is in Monument Valley and you can only get this close if you are accompanied by a guide. It is, like so much of the landscape, particularly sacred for the Native Americans and I felt tingly as our guide played a traditional pipe while lying underneath the opening.
The second is Window Rock, where Navajo Nation have their assembly /Parliament buildings and administration. If you look closely you might be able to spot people who have climbed up to the hole. Not for the faint hearted!
Have a great day.