Behind the Théâtre Antique, the Colline Saint-Eutrope rises about 100 metres above town. Once the site of the Princes of Orange's fortified castle (demolished by Louis XIV in 1673 after the king annexed the principality), it is now a wooded municipal park crisscrossed by paths and shaded by mature pines.
From the orientation table at the top, the view sweeps over the cavea of the Roman theatre directly below, across the tiled roofs of the old town, and out to Mont Ventoux on a clear day. A few weathered fragments of the old castle survive among the trees. The climb takes 15 minutes from the theatre on foot; the path is steep but well-marked.