Eburobrittium is the Roman site near Óbidos, a reminder that the walled medieval town is only one layer of settlement in this part of Portugal. The remains are low and archaeological rather than spectacular, but they add depth to a visit focused on castles and whitewashed lanes.
It is best for travellers with a real interest in ancient history or a car-based day around Óbidos. Check access locally before setting out, as facilities and interpretation are limited compared with the town's main sights.