The Roman bridge across the Guadiana is one of those Roman structures that asks you to imagine the scale of the empire. It is enormous: a long shallow arc of granite arches stepping across the river, anchored at the southern bank by the ninth-century Alcazaba fortress and at the northern end by the Plaza de España and the old town. Twenty centuries of floods, repairs, and reconstructions have left the structure a patchwork — visible if you walk along it — but the line is still essentially Roman.
The bridge is now pedestrianised and is the best place in Mérida for a sunset walk. Cross to the south bank and look back: the Alcazaba in the foreground, the cathedral tower behind it, the old town rising in pale stone. Calatrava's white cable-stayed Puente Lusitania carries the modern traffic a few hundred metres downstream — the contrast is the point.