Way back when Geocaching was a youth.
They use to have a link called Placenames in one of the map sections.
It would show nearby POI's, Historical Places and many other things and included an approximate distance to it.
You may also want to create a group that is managed like the Flickr group and have the places the focus of the group.
But I do not think a category just for them is all that good of an idea as mentioned it might become a hodge podge of unwanted marks.