On Saturday, walking along Constitution Avenue, I heard the phangom beat of drums. Outside of the Sculpture Garden, I found the source:
Those are big paint tubs of various sizes, stacked in various thicknesses, and a garbage can sitting on traffic cones. He used sawed off broom handles as sticks, and would tap on parts of the grocery buggy to substitute for chimes and cymbals. He kept a steady, powerful beat for as long as I heard him, which was for approximately 15 minutes.