Museo de la Massacre de Ponce (corner of Calle Marina and Calle Aurora, 787/844-9722, Tues.–Sun. 8 a.m.–4:30 p.m., free), has a very modest exhibit in Spanish dedicated to the memory of a bloody incident on Palm Sunday in 1937 when local police were ordered to fire on Puerto Rican Nationalists demonstrating for Puerto Rico [1]’s independence from the United States. Nineteen people were killed and more than 200 were injured.
Links:
[1] http://www.moon.com/destinations/puerto-rico