Here is an article about La Gran Piedra:
"HAVANA TIMES, — Formed most likely from a volcanic rupture, the “Gran Piedra” (the Grand Stone) is an enormous rock measuring 51 yards long and 25 to 30 yards wide. With a calculated weight of 63,000 tons, this boulder is situated on the summit of a mountain rising 1,225 meters above sea level. The site is located 25 kilometers (16 miles) southeast from the city of Santiago de Cuba."
Photos I have taken: