Built by the obsessively pious Louis IX, this Gothic jewel is home to the oldest stained-glass windows in Paris. The chapel was constructed over three years, at phenomenal expense, to house the king’s collection of relics acquired from the impoverished emperor of Constantinople. The upper chapel is where the famed beauty of Sainte-Chapelle comes alive: 6,458 square feet of stained glass is delicately supported by painted stonework that seems to disappear in the colourful light streaming through the windows. Deep reds and blues dominate the background glass, noticeably different from later, lighter medieval styles such as those in Notre-Dame’s rose windows. One poetic writer put it “the most marvellous coloured and moving air ever held within four walls”. Visit in the afternoon to enable the sun to maximise the effect of the glass. Adults 8Euros under 18’s free.