2
Good evening,For Medellin, it's a huge city with a vibrant nightlife. You have a lot of activities in the city and also outside (for a day or more)
San Gil is the hub of outside sports or activities. You have also some others possibilities (villages or places) like Barichara (it's not the only one) for visiting.
It could be San Gil and Medellin. Between Cartagena and Medellin, you can stop in Mompox (but it's time consuming to reach it)
Michel
