On a budget, Conciergerie still earns its price.
€13 (combo with Sainte-Chapelle €20; free under 18 / EU under 26)
A soaring Gothic hall opens into the dark history of the Revolution, including Marie Antoinette's cell. The HistoPad augmented-reality tablet brings the empty stone rooms to life. Often quiet, and a natural combo with neighbouring Sainte-Chapelle.