From the outside, the Cathédrale St-Jean appears solid and determined, having withstood the sieges of time, revolution, and war. Its apse is a masterpiece of Lyonnais Romanesque architecture.Inside the cathedral, architectural highlights include the fabulous 13th-century stained-glass windows in the choir and the varied window tracery and vaulting in the side chapels.The most unique and interesting feature of Lyon''s cathedral is the 14th-century astronomical clock, in the north transept.