We sailed in past the modern skyline and suddenly the old fortifications appeared like something from Pirates of the Caribbean. The cruise terminal is a 10-minute taxi into the walled city, and the second we passed through the clock tower gate I knew this day would rank top-five ever. The streets are a maze of mustard-yellow churches, emerald-green balconies, and palenqueras in fruit-bowl hats offering photos (tip them!).

When Pedro de Heredia founded this city on June 1, 1533, he built it atop an indigenous settlement that had thrived here since 4000 BC. Within decades, Cartagena became the Spanish Empire's most critical New World port—so much gold and silver flowed through here that it drew every pirate in the Caribbean like moths to a flame. Sir Francis Drake sacked the city in 1586, and the Spanish learned their lesson: they began building walls that very year. It took nearly two hundred years to complete those fortifications—11 kilometers of stone, over 20 feet tall, finished in 1796. Standing on those ramparts at sunset, knowing they've watched over this harbor for more than two centuries, gave me chills.

We made the climb up to Castillo San Felipe de Barajas the next morning, and I finally understood why they call it a masterpiece of Spanish military engineering. Built in 1536 and massively expanded in 1657, it's the largest Spanish colonial fortress in the Americas—a maze of tunnels designed so defenders could hear enemy footsteps approaching from below. I walked those underground passages with a guide who told stories of sieges that never succeeded, of cannons that never had to fire because the fortress itself was deterrent enough. UNESCO declared this entire walled city a World Heritage Site in 1984, recognizing it as the most extensive fortifications in South America.

The walled city is divided into three distinct neighborhoods, each with its own character. San Pedro was the aristocratic quarter—you can still see the cathedral and those gorgeous Andalusian palaces with their wooden balconies and hidden courtyards. San Diego housed the merchants and middle class, their homes slightly smaller but just as charming. Getsemaní, the popular quarter outside the walls, was historically working-class; today it's the heart of Cartagena's creative soul. I entered through the Torre del Reloj, that iconic yellow clock tower that's been the main gate since colonial times, and walked through Plaza de los Coches—once a slave market, now a square ringed with cafés where locals play cards and tourists sip tinto coffee.

We walked the walls at golden hour first — 500-year-old ramparts with cannons still pointing at the sea, breeze carrying arepa smells and salsa music. Then wandered Getsemaní neighborhood — street art exploding on every wall, locals playing dominoes on plastic chairs, kids kicking soccer balls. Plaza de la Trinidad at dusk was pure joy: food carts, dancers, and a 10-year-old who schooled everyone at breakdancing.

Lunch was at La Cevicheria (Anthony Bourdain's favorite) — octopus ceviche so fresh it tasted like the ocean, coconut lemonade that should be illegal. Afternoon was the Gold Museum (free!) and then the Inquisition Palace — creepy instruments but fascinating history. Ended with sunset from Café del Mar on the walls — passionfruit mojitos while the sky turned neon over the Caribbean.

The pros: insanely photogenic, incredible food, and locals who are proud and welcoming.

The cons: hot and humid weather, and street vendors can be persistent (though a polite "no gracias" works well).

Practical tips: Wear light clothing and comfortable shoes — the cobblestones are brutal. Stay in the walled city and Getsemaní — perfectly safe and vibrant. Use only official yellow taxis or Uber.