I was super excited to see Cartagena, a gorgeous Spanish colonial city on the Caribbean Sea. I thought I’d spend 5 nights here. I was planning to until I had to move up a future destination. So I only had 3 nights. It was enough although I had to cut out a jaunt to some outlying islands where I probably could’ve found some decent scuba diving (I need my fix).  
A couple things about Cartagena: 

(1) Cartagena is an outlier in Colombia as it’s expensive with prices nearing US levels. Which is a bummer.

(2) I was forewarned in the coffee country about the heat. I spent months in SE Asia so I admittedly shrugged it off. It’s MF hot in Cartagena. When you’re on the equator, that sun is just so goddam strong. So my schedule in Cartagena went something like this: sleep til 8, eat breakfast & hit the city by 9am before it’s scorching hot. Lunch at 1ish & then spend the rest of the afternoon in the shade on the rooftop of my hotel or lounge by the pool. Anything to get out of the sun. I’d come back to life around 5 & head out again to wander & enjoy the night.  
The thing to do in Cartagena is wander. Wandering photogenic cities just so happens to be my favorite thing to do traveling, taking pitstops along the way in gorgeous chill plazas at coffee shops, restos & bars. It’s impossible to get lost as long as you stay in the old town as it’s fortified by large stone walls. The city is lovely & it reminded me a bit of Havana with its picturesque winding streets although the difference is Cartagena is a pristine colonial town unlike the dilapidated Havana (which in my opinion, just adds to its romanticism). I’m not sure there will ever be a more charming city than Havana so I should probably just remove it from any future equations.