Berlin has two rental markets operating simultaneously in the same city. Long-term tenants — those who have been in their apartments for years — pay an average of €8.50 per square metre. New tenants pay €15.80. State housing company tenants pay below €7.00.

The result is a city of people who cannot afford to move. Economists call this the "lock-in effect." Berliners call it luck. The practical consequence for anyone arriving in Berlin is simple: the apartment your colleague pays €900 for is not the one you will find available. The one available is the one at €1,800.

This gap — between what existing tenants pay and what new arrivals must pay — is, quietly, one of the most significant social divisions in the city. It is also why Berlin's rental market will remain competitive for the foreseeable future, regardless of what the headline numbers say.