The Château Fort de Lourdes sits on a rocky outcrop 80 metres above the town, commanding views across the Pyrenean foothills in all directions. The castle has a complex history that predates the pilgrimages by centuries — it was a fortified strongpoint through the medieval period, passed between the counts of Bigorre, the English, and the French kings, and served variously as a royal fortress and state prison before being converted to its current use as the Musée Pyrénéen.
The Musée Pyrénéen inside the castle is a solid regional museum covering the natural history, archaeology, folklore, and traditions of the Pyrenees. Exhibits include period costumes, agricultural tools, an extensive collection of crèche figures, and displays on the mountain ecology. The castle's towers and battlements are accessible, and the views from the top — across Lourdes to the sanctuary and the mountain peaks beyond — are the best in the area. The castle is about a 10-minute walk from the sanctuary.