Paris city officials are knocking on doors in Montmartre.

Key lockboxes on every door. Residents describing their building as "a living hell."What they found: a block full of illegal Airbnbs.Fortune's new investigation makes it clear Paris is ground zero for Europe's STR crackdown. And the city isn't bluffing.→ The annual cap is now 90 nights (down from 180) → France's supreme court ruled platforms are legally liable for illegal listings → Two hosts were fined €80k and €150k in February alone → The deputy mayor's target: reclaim 20,000 apartmentsAirbnb is adapting pivoting growth to Brazil and India, and stacking experiences and services onto the platform to protect revenue.But the bigger shift is coming continent-wide.EU Regulation 2024/1028 goes live on 20 May. Platforms will be required to share host data with authorities across all 27 member states. Every city gets Paris's enforcement toolkit.The era of regulatory arbitrage in European STR is ending.