Conciergerie

The Conciergerie is where French history got darkest - this former royal palace became the antechamber to the guillotine during the Terror. You'll see Marie Antoinette's actual prison cell, recreated with period furniture and a black crucifix, plus the communal cells where ordinary prisoners slept on straw. The highlight is the massive Gothic Hall of the Men-at-Arms with its ribbed vaulting - it's genuinely impressive medieval architecture that predates Notre-Dame.

The visit flows chronologically from medieval palace to revolutionary tribunal. Interactive tablets work well here, explaining how the building functioned as both courthouse and prison. The reconstruct courtyard where prisoners took their final walk is sobering. The cell recreations vary in quality - Marie Antoinette's is atmospheric, but some others feel overly theatrical with wax figures.

Honestly, this works better as historical context than standalone attraction. If you're doing Sainte-Chapelle anyway, the combo ticket makes sense, but I wouldn't prioritize it over Musée Carnavalet for French history. The medieval halls are the real draw - spend your time there rather than rushing through all the Revolution displays. Winter visits feel more appropriate given the somber subject matter.