In the picture there is one of about two hundred spherical "rocks", some which are up to 27 feet in diameter. Where are they located?

Known as "Rock City", it is a registered national landmark near Minneapolis, Kansas.

This 5 acre park is home to about 200 of these calcite-cemented concretions. The very large rocks are made of sandstone from the Dakota Formation, deposited along the edge of a Cretaceous sea about 100 million years ago. Over time, circulating water deposited a limey cement between the sand grains, creating harder bodies of sandstone called concretions. They consist of medium grained sandstone and calcite. The sandstone is more than 95% quartz sand of which 20% of the original sandstone has been replaced by calcite.I have been there several times and is a very unique place to visit in Kansas.