The best strategy is to buy a timed-entry ticket online in advance via the official Catacombs site. Tickets open exactly 7 days before your intended visit, with slots selling out quickly. The site strictly limits entry to 200 people per time slot, and walk-ins are largely unavailable—even if the website indicates otherwise.

Timed entry slots start at 9:45 a.m., and the attraction runs until 8:30 p.m. (last admission at 7:30 p.m.). It’s closed on Mondays, as well as January 1, May 1, and December 25.

To avoid long lines (which can exceed 2–3 hours), aim for one of the earliest time slots in the morning or the last slots in the evening. Crowds are noticeably thinner Wednesday through Friday and during off-peak months (October through April).

On arrival, you’ll descend 131 staircase steps, weave through 1 km of ossuary galleries (containing meticulously arranged human bones), and climb 112 steps out again. A constant temperature of about 14 °C calls for a sweater—even on warm days. Bring comfortable shoes, avoid large bags, strollers, tripods, or food & drink (none are allowed inside), and note that toilets are only available outside the entrance.

To make your descent into history sharp and well-organized: book the official online ticket exactly 7 days in advance, arrive just before your slot, choose early or late weekday visits, and be prepared for the cool, claustrophobic walk through the tunnels. The Catacombs aren’t just a sight—they’re a subterranean story of centuries beneath Paris.