Final answer:
The statement regarding Old San Juan's historical defensiveness and the symbolism of its garitas is true. El Morro and other Spanish forts, like Castillo de San Marcos in Florida, were built to protect against European rivals and piracy.
Step-by-step explanation:
The statement about Old San Juan being a Spanish colonial city surrounded by a wall to protect it from invasions, and having El Morro as the main fort with garitas that guarded the bay is true. The garitas are indeed a national symbol of Puerto Rico. The fortifications of Old San Juan, such as the El Morro fort, were instrumental in defending against invaders, notably during the era of Caribbean piracy and later imperial conflicts. Castillo de San Marcos, constructed in a different period and location (St. Augustine, Florida), mirrors the defensive designs seen in Puerto Rico, serving to protect Spanish interests against European rivals and local threats.
Throughout history, Spanish colonial cities were strategically designed with fortifications and a central plaza surrounded by significant buildings, including a Catholic church. This pattern was indicative of the importance of defense and governance in the Spanish Empire's urban design. The construction of such fortifications, including El Morro in San Juan and the Castillo de San Marcos in Florida, was a direct response to the need for protection against imperial challengers and piracy.