The Old San Juan. The colonial district of the Puertorrican capital has recently been named a Historical Monument of the United States, which only magnifies the formerly Spanish city's legacy. The old colonial district has been included in tourist routes taken by lovers of architecture ever since it was made a Unesco World Heritage Site in 1983. The location includes the walls and forts of San Felipe de Morro and San Cristobal. Local authorities believe the push given by the United States will help Puerto Rico become one of the biggest tourist locations in the Caribbean.