The 12th-century interior of this deconsecrated church is a hauntingly atmospheric setting for summertime opera and concert recitals (www.puccinielasualucca.com), staged daily at 7pm; buy tickets (adult/reduced €25/20) in advance inside the church or at a cheaper rate before 6pm from the tourist office – €20 instead of €25.
In the north transept, the Gothic baptistry crowns an archaeological area comprising five building levels going back to the Roman period. Don't miss the hike up the red-brick bell tower.