Belize Adventure has a nice article about El Pilar.
"The name of El Pilar means watering basin, which is quite understandable if you consider the location of this ancient city. If you want to pinpoint the exact location of this ancient Mayan city, it’s safe to note that you can access it via San Ignacio as well as the Bullet Tree Falls. These are placed on the Belize River. Many underground streams are found here and that’s the reason why you will find an abundance of vegetation in this particular location. Again, this is understandable if you take into consideration the uniqueness of this place and the amazing benefits that it can deliver for any visitor."