The twin towers of Bayonne's Gothic cathedral soar above the city. Construction began in the 13th century, and was completed in 1451; the mismatched materials in some ways resemble Lego blocks. Above the north aisle are three lovely stained-glass windows; the oldest, in the Chapelle St-Jérôme, dates from 1531. The entrance to the stately 13th-century cloister is on place Louis Pasteur.