The narrow streets squeeze between multistoried dwellings. Their New Orleans-style balconies, festooned with plants and decorations, will keep your camera pointing upward. Shops with labels in English and Spanish treat visitors to a variety of gifts and antiques, while familiar fast food signs offer Wendy’s or Burger King sandwiches. Tourists throng the cobblestones, climbing the steep streets for frequent, rewarding glimpses of the gleaming bay on one side and the azure ocean on the other.

At first glance, the enclave of Old San Juan (welcome.topuertorico.org/city/sanjuan.shtml), whose piers are frequently lined with towering pleasure ships, offers a typical cruise stop (for ships that call at San Juan, see http://www.americasvacationcenter.com/Cruises/). The festive island milieu, while not significantly different from other such ports, has lots to offer: The shopping is relatively low-priced (even a Marshalls department store for steep discounts), and restaurants are plentiful. Since Puerto Rico is a territory of the United States, U.S. dollars are accepted everywhere, and English is almost ubiquitous.

On closer inspection, however, the area offers the inquisitive visitor something more: dramatic signs of a rich history that can make one wonder about the human condition. The old city’s compact space easily can be explored within the confines of a daylong cruise stop.

First tip: Ignore the throng of offers for tours  (unless you choose to visit the impressive El Yunque rainforest, which will reward you in other ways but take your entire day). Instead, consider a self-guided walk (www.gotopuertorico.com/go_cultureHistory.

php?language=english&page=55). The cruise ships tie up near La Casita, the information headquarters for the area, which offers free booklets detailing walking tours.

Second tip: On a recent visit, the directions at the beginning of the walking tour were out of date. I recommend skipping directly to the two historic forts (www.cr.nps.gov/nr/twhp/wwwlps/lessons/60sanjuan/60sanjuan.htm) that once made Old San Juan a key post of the Spanish empire, and later a player in World War II. They are run by the National Park Service and well worth a $3 ticket for a walk-through ($5 if you go to both).

Puerto Rico first came to European attention in 1493 during Columbus’ second visit to the New World. Interestingly, he named the island San Juan Bautista (St. John the Baptist); Ponce de Leon, who conquered the island in 1508, named the beautiful harbor later encircled by the city, Puerto Rico, a rich or fine port. At some point in history the names were switched, with the island becoming Puerto Rico, and the city labeled San Juan.

The closest fort, the Castillo de San Cristobal, dominates the hill just past the Plaza de Colon. Exhibits on the ground floor focus on 16th and 17th-century efforts by the Spanish to consolidate their holdings in the New World — holdings that extended throughout the Caribbean and Central and South America, enriching the conquerors and enslaving the inhabitants.

The fort’s central plaza once saw drilling formations, first of Spanish, then of native Puerto Rican troops, whose elegant white uniforms and gilded tricorn hats are also on exhibit inside a series of windswept rooms that once served as mess halls and 10-in-1-bed barracks.

Climbing to the sunwashed second level, the visitor is greeted with a sweeping vista of ocean and town. The bulwarks have ramps behind them, upon which the sharpshooters climbed to fire, then ducked back down to reload. Between them are slots for the cannons. A number of these weapons are displayed on the lower level; they had to be painfully winched up a ramp, then rolled from shaft to shaft as needed. A bell-like sentry post affords an exciting view of rolling surf and the fort’s sheer wall to the sea.

Underneath it all, a low-roofed tunnel winds inward for several hundred feet toward the water’s edge. It was used to bring in and store munitions, and the ceiling was booby-trapped to collapse on invaders.

An underground alley off to the right leads to a dungeon that delights kids as much as it gives their parents the willies. Ancient graffiti scratched into the rock walls records prisoners’ names, dates and pictures of their ships. Researchers have protected much of the writing under plexiglass while they examine it.

El Morro, the second fort across town, has in its latest (1800s) design an even more elaborate setup for harbor defense: batteries of cannons on four different levels.

All this seems very peaceful on a sunny afternoon, as laughing children and mellow adults stroll under snapping flags. But it can certainly give one pause, even if just to reflect on how a monument to ruthless domination has been turned into a patriotic attraction. The NPS guidebook gives just one paragraph to the oppressive labor that must have gone into constructing such fortresses (walls 18 to 40 feet thick) without benefit of backhoes or cranes.

Guidebooks also gloss over American intervention, which wrested control of the island during the Spanish-American War (www.loc.gov/rr/hispanic/1898/). However, the exhibits of photos and news coverage of the time do include Spanish-language editorial cartoons showing a rapacious Uncle Sam, first making an omelet of crushed Spanish territories, then beheading Cuba, while a trembling Puerto Rico awaits its turn.

No matter what you make of these marvels of military ingenuity, the forts offer an educational slant to a fascinating island day. You’re sure to ponder the lessons over dinner.

Emerging back into modern times, we turned our attention to present-day concerns. There was still time for a little shopping, and then delicious lunch at the Tamarind, where we enjoyed Ecuadorian shrimp parfait and fried egg tortilla.

Happy Traveling!

Photos: 1. New Orleans-style balconies line the narrow streets.

                  2. Towering cruise ships of many nations call daily.

                  3. Piers are full (a new one is under construction).

                  4. Old-world lamps provide a charming touch.

                  5. The Castillo de San Cristobal dominates a hill over the town.

                  6. A bell-like sentry post provided early warning.