El Morrillo is one of the fortresses built in the 18th century to protect the city from attacks by corsairs and pirates. It is a colonial military building in whose surroundings the revolutionaries Antonio Guiteras and Carlos Aponte (Venezuelan) died in combat on May 8, 1935.

Today it is a memorial-museum and the remains of both fighters rest inside such place. It shows personal objects of Antonio Guiteras and Carlos Aponte, who were outstanding political figures during the first half of the 20th century.
The museum exhibits archeological artifacts from aboriginal cultures, since it was built on the largest aboriginal settlement.