A 30-minute walk west of the city centre on the southern river bank, this monastery was once among the most prominent in Spain. Founded in 1187 by Eleanor of Aquitaine, daughter of Henry II of England and wife of Alfonso VIII of Castilla, it's still home to 35 Cistercian nuns. Entry is via one-hour guided tour only – unhelpfully, the timing of the tours is decided only at the beginning of each session, so it's worth ringing ahead.
This veritable royal pantheon contains the tombs of numerous kings and queens, as well as a spectacular gilded Renaissance altar. The highlight, though, is the Museo de Ricas Telas, reached via a lovely Romanesque cloister and containing bejewelled robes and royal garments.
To get here, follow the river via Calle de la Merced and turn left on Avenida Monasterio de las Huelgas; the monastery is signposted.