As you pass this pink façade on Plaza del Ayuntamiento, do not mistake it for just an outdoor café. This is the Roman Theatre Museum. Museo del Teatro Romano deserves to be at the top of your must-see list. Inside are Roman artifacts found from their 634 year reign over the city from 209 BC until 425 AD. The interactive displays explain the history of the Roman occupation. Then follow the tunnel to the historical highlight of Cartagena: the ruins of the ancient Roman Theatre.