Last month I spent a day in San Juan, Puerto Rico. There you’ll find “Old San Juan:” the neighborhood that dates back to the Spanish conquistador era. Atop a hill overlooking this area town is “EL Morro” an enormous Spanish fort constructed between the 16th and 18th centuries. A very, very cool citadel.

To the Puerto Ricans it’s a place of “national” pride. Many of the placards in the site make reference to the former might of this arsenal, and emphasize the powerful legacy of imperial Spain. But how Spanish might relates to local pride is unclear. Spain for its part arrived in 1494, promptly killed all the original inhabitants, and repopulated the island with indian subjects from elsewhere in their American empire. So whether current Puerto Ricans identify with colonizer or colonized in this case, I know not. Regardless, it's a popular place.
Geopolitical history: due to Caribbean wind patterns, if you’re a ship coming from Europe, Puerto Rico is first the island you encounter with fresh water (important after a long Atlantic trek). Now on Puerto Rico, there’s only one place suitable for a major harbor: the San Juan bay. Harbors are important if you want your ship to stay anchored during a storm. The bay itself has a relatively small mouth, so control it and you thus control the bay, thus the island, and thus all of the Caribbean, so the logic went.
Here is a picture of that bay mouth, which the fort overlooks with its scores of gunports.

Here is a picture of a passing ship, taken from one of those gunports.

Here is a pic of a port with a gun still in it. Think you could hit that ship from here? If not, no worries! El Morro had 50+ cannon posts, so I think as a whole its odds were pretty good.

In sum, it’s one of old Spain’s most impressive military engineering feats. As such it kept the island safe for over 400 years. Despite numerous attacks, no imperial rival was ever able to best the fortifications of “El Morro.”
At least not until 1898. That year the U.S.A., fresh with global ambitions and cutting edge battleships, laid waste to the Spanish defenses within a few hours. The attack was part of the larger Spanish-American War, wherein the adolescent America decided it was now strong enough to piss with the imperial big dogs, and proved it by beating up on the by-then-moribund Spanish empire, taking Puerto Rico, Cuba, and the Philippines all within six weeks.
We’ve since given up on the later two of those territories, but to this day Puerto Rico remains a U.S. “protectorate” (a euphemism for colony). As a colony, the island uses U.S. dollars, the U.S. Postal Service, U.S. phone services, and this:

And that’s the most interesting part. In addition to the questionable legitimacy of a public history story which emphasizes P.R. nationalism by drawing upon the might of a former conqueror, the site itself is managed by a successive conqueror! After demolishing large parts of the fort with big battleship bombs, the U.S. spent lots of money in the 20th century restoring “El Morro” to its former condition. Today the Department of the Interior maintains the area. And despite National Park Service's out-of-place pine tree logo in front of the building, the role of the U.S. government is largely silent within the fort’s historical presentations.
Fool me once, shame on you. But fool me twice…