If a need were to arise to move a stone of that size, say building a road; it could be a good idea to drill a couple of holes into that soft limestone to move it with a crane and rigging. Just a thought. Perhaps the last one remaining and it was so big they just left it in the median?

Ok, lets suppose that despite Byrd's comment about the last dunking of the area, and that at some time it was close enough to a water way to be of use.

Those holes are remarkably well preserved, and little other form to the stone.
Generally, I believe moor lines are in line with each other, more or less.

So... dunno what it's from. But it doesn't seem to be 6,000 years old.