Saint-Eustache took 105 years to build, and the delay shows in the stonework: Gothic vaults come down onto rows of round classical columns instead of Gothic piers. The lower half of each pillar is a classical column ringed with carved tiers; above, the shaft splits into ribs that fan across a ceiling 33 metres up. Inside it is wide, high and dim, and you can walk a full circuit of chapels behind the altar without retracing your steps.
This was the parish church of Les Halles, the food market that filled the streets outside, and the guilds of that market paid for chapels of their own. The market moved out to the suburbs in 1969 and the quarter has never quite replaced it. Inside, a painted sculpture shows porters carrying off the last crates. The plan copies Notre-Dame — tall nave, doubled side aisles, a ring of chapels round the choir — so the space reads as familiar even on a first visit. Stay for the organ if the hours allow: it is one of the largest in France, and the church programmes it hard.