Three of San Juan's hidden hot spots

Amazingly, Puerto Rico's capital city of San Juan is actually the oldest city under U.S. governance, established in 1508 by explorer Juan Ponce de Leon. Since these early beginnings, San Juan has grown into a vibrant and exciting city packed with adventure. Here are a few of the city's most notable sites for you to enjoy when you visit Puerto Rico on a Caribbean cruise.

Old San Juan
If you want to get a first-hand sense of what life was like in the city's infancy, be sure to head into the neighborhood of Old San Juan, an area that's nearly 465 years old. With an attractive blend of residential and commercial buildings, you'll feel like you're walking back through the pages of history as you stroll down the streets paved with blue cobblestones and pass by Spanish-colonial structures that have been accurately restored.

Overlooking the sea from the west end of the neighborhood lies Fort San Felipe del Morro, a small fortification featuring 16th century battlements and an impressive lighthouse. Named for King Philip II of Spain, the fort was meant to defend San Juan from sea invasion. Here, you can explore the dungeons, barracks, tunnels and ramps that make up the site.

El Yunque National Rainforest
Tell the Amazon to move over, because Puerto Rico's El Yunque National Rainforest is a sight to behold. Named after the Native American spirit of Yuquiyu, a protective force believed to have lived atop a mountain at the heart of the rainforest, El Yunque is a lush and mountainous region in the heart of Puerto Rico, and is the only rainforest in the U.S. National Park System.

The area is actually comprised of five unique forests, which includes a cloud forest as well as a dwarf forest that features an assortment of miniature trees and flora. You can also catch a glimpse of the island's tree frog, a rare sight for even the most adventurous rainforest explorers. Though El Yunque only covers a small portion of the island, it is one of Puerto Rico's most treasured and beautiful natural resources.

Fort San Cristobal
Fort San Cristobal is an impressive military structure built to encompass the entire city of San Juan. Fort San Cristobal was completed in 1783 and covers more than 27 acres, making it the largest fortification constructed by Spanish colonists on Puerto Rico by far. While sections of the fort have since been demolished and reduced to allow greater sea access to the city, the battlements remain picturesque sights in the layout of San Juan, reminding citizens and travelers of the rich colonial history that brought Puerto Rico into the modern age. You can tour the fort while taking in military drills and annual reenactments and exploring the vast labyrinth of tunnels and fortifications used by Spanish soldiers to defend San Juan.

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Lighthouse and fort in Old San Juan, Puerto Rico
Lighthouse and fort in Old San Juan, Puerto Rico