Start with the clock, not the map
The walled city is small enough to cross end to end in about an hour if you don't stop, which is exactly why most people get it wrong. The route is not the problem. The hour is. Cartagena sits at ten degrees north, the humidity sits between 75 and 85 percent whatever the season, and the cobblestones give the heat straight back at you.
So: 7:30 to 10am, or 4pm until the light goes at around six. In the morning the plazas are empty, the cruise groups haven't landed, and the east-facing walls throw real shade. In the late afternoon you get the gold light and the walls lit up for sunset. Between eleven and three, plan indoor stops or don't go.
We set guests off on this walk on their day in town, and the brief we give is always the same. Two to three hours, five stops, water in the bag, and nothing booked.
Stop one: Torre del Reloj and Plaza de los Coches
Start at the Torre del Reloj, the yellow clock-tower gate that is the historic main entrance to the walled city. It's the easiest landmark in Cartagena to name to a driver, and it's where every guided group assembles, which is a good reason to be there before they are. The tower stands on a seventeenth-century base; the clock mechanism itself is Swiss, fitted in the late nineteenth century.
Step through and you're in Plaza de los Coches, a triangular plaza that was the city's colonial slave market. That history is not signposted with much force, and it's worth standing still with for a minute before the candy sellers of the Portal de los Dulces get your attention. They sell cocadas, bocadillos and tamarind balls along the colonnade. Buy the cocadas, five minutes, move on.
Stop two: Plaza de la Aduana
The largest plaza inside the walls, and the one with the least to do in it. That's not a criticism. It's a civic space rather than a social one, anchored by the old Royal Customs House, and it's where Spanish colonial administration physically sat. Walk across it slowly rather than looking for a bench. Five to ten minutes is honest.
It's also the moment the scale of the place registers, which the narrow streets on either side don't let you feel.
Stop three: Palacio de la Inquisición
The one paid interior we'd argue for, at around COP 24,000 for an adult. It's the former seat of the Holy Office tribunal, and the building itself, with its stone doorway and carved balconies, is as much the exhibit as the collection inside. Set expectations: a good deal of the interpretation is in Spanish, and visitors who want a full English narrative come away disappointed.
It's also air-conditioned in parts, which makes it the correct place to be if you have misjudged your timing and find yourself walking at noon.
Stop four: Las Bóvedas
Twenty-three vaulted chambers and forty-seven arches built into the city wall between 1792 and 1796, the last Spanish colonial construction raised inside Cartagena's defences. They were storerooms and, later, cells. Today each vault holds a craft shop.
Entry is free. The shopping is frankly aimed at cruise passengers and you can skip every stall without regret, but the architecture is the reason to come: a continuous run of arches at the northern end of the walls, and the easiest point to get yourself up onto the ramparts.
Stop five: the walls themselves, at sunset
Finish on top of the wall. The ramparts are continuous along much of the northern and western edge, the Baluarte de Santo Domingo among them, and they're part of the same World Heritage fortification system as the hilltop castle and the forts out at Bocachica. There's no ticket to walk them.
Go up in the last hour of daylight, walk west with the sea on your right, and stop when you find a stretch you like. This is the part of the day guests tell us about afterwards, and it's the free one.
Guide or no guide
Walking it yourself costs nothing. A licensed guide typically asks COP 80,000 to 150,000 per group for two to three hours, agreed before you set off rather than after, and what you're buying is historical depth the plaques don't give you. Either is defensible. What we'd avoid is accepting a guide who approaches you mid-walk without settling the number first.
Doing this from Barú
We're on Bahía de Cholón, out on Barú, and the crossing to Cartagena runs thirty minutes to an hour on our boat. For the morning version of this walk, that means an early start and breakfast moving with you. For the sunset version it's easier: go in the afternoon, walk the walls as the light drops, eat in town, come back after.
One thing to settle in advance. Our boat has limited capacity, so reserve your place rather than turning up for it. Without a reservation, the wait for the next crossing can be long.