Santo Domingo holds the oldest continuously inhabited European settlement in the Americas. The Zona Colonial — its cathedral, the Alcázar de Colón and Calle Las Damas — is a UNESCO World Heritage site you can walk end to end in an afternoon.
It is a three-hour drive west from Punta Cana, and day tours combine the colonial centre with the Malecón and lunch in the old town. Wear comfortable shoes: the streets are cobbled and the tour is mostly on foot.