2 Best Sights in St-Germain-des-Pres, Paris

Dubbed the Cathedral of the Rive Gauche, this enormous 17th-century Baroque church has entertained some unlikely christenings—among them those of the Marquis de Sade and Charles Baudelaire—as well as the nuptials of novelist Victor Hugo. More recently, the church played a supporting role in the best-selling novel The Da Vinci Code, and it now draws scores of tourists to its obelisk (part of a gnomon, a device used to determine exact time and the equinoxes, built in the 1730s). Other notable features include the exterior’s asymmetrical towers and two magnificent Delacroix frescoes, which can be seen in a chapel to the right of the entrance. In the square just in front, view Visconti’s magnificent 19th-century fountain—it's especially beautiful at night.

Paris's oldest church was built to shelter a simple shard of wood, said to be a relic of Jesus's cross brought back from Spain in AD 542. Vikings came down the Seine and sacked the sanctuary, and Revolutionaries used it to store gunpowder. Yet the elegant building has defied history's abuses: its 11th-century Romanesque tower continues to be the central symbol of the neighborhood. The colorful 19th-century frescoes in the nave are by Hippolyte Flandrin, a pupil of the classical master Ingres, while the Saint-Benoit chapel contains the tomb of philosopher René Descartes. Step inside for spiritual nourishment, or pause in the square to people-watch—there's usually a street musician tucked against the church wall, out of the wind. The church also stages superb organ concerts and recitals; see the website for details.