Mexican Hat is a name of a curiously sombrero-shaped rock and a small town located in its vicinity. It is on U.S. Route 163 three miles (5 km) south of the junction with State Route 261, just outside the northern boundary of Monument Valley.
We did not stop there as we were in a hurry to get to Natural Bridges SP before the sunset. Even the photo below I took from the car while we were still driving, so it might be a bit blurry: