Criterion (vi): La Fortaleza and San Juan National Historic Site outstandingly illustrate the adaptation to the Caribbean context of European developments in military architecture from the 16th to 20th centuries. IntegrityLocated within the boundaries of La Fortaleza and San Juan National Historic Site in Puerto Rico are all the elements necessary to understand and express the Outstanding Universal Value of the property, including La Fortaleza, Castillo San Felipe del Morro, Castillo San Cristóbal, San Juan de la Cruz (El Cañuelo) fort, and a large portion of the original San Juan City Wall, including San Juan Gate. AuthenticityLa Fortaleza and San Juan National Historic Site in Puerto Rico is authentic in terms of its forms and designs, materials and substance, and location and setting. La Fortaleza is protected under the regulations of the Puerto Rico Legislative Assembly, as well as by the Commission of the Historic Zone of San Juan, an independent commission of the Capital of Puerto Rico. The inclusion in 2013 of both La Fortaleza and San Juan National Historic Site within the Old San Juan Historic District National Historic Landmark affords another level of protection as well.