New York

New York is every English on earth in one subway car — the Yiddishisms of the Upper West Side, the Italian-American consonants of Bensonhurst, the Caribbean-Brooklyn lilt of Crown Heights, the Dominican Spanish-into-English codeswitch of Washington Heights, and the Midwest-flat newsreader voice of every transplant who arrived three years ago. For learners, no city compresses more registers into a one-mile walk.

The volume of practice is the unfair advantage. Thirty meet-ups a week — Toastmasters, Bumble BFF, language exchanges in every Manhattan and Brooklyn neighbourhood — plus a public library system with free conversation circles, NYU/Columbia open-enrolment classes, and an improv-comedy scene (UCB, Magnet, Cellar) that doubles as accent-and-timing practice. Stretch four months and your spoken English is performing at the level most learners need a year of London for.

The cultural firehose is unlike anywhere else: a $30 standing ticket at the Met, free Friday nights at MoMA, a Broadway lottery you can win on your phone, and the densest comedy-club calendar on earth. The catch is the cost — $4,200/month is a serious commitment — and the city's brutal indifference. New York rewards assertive learners who throw themselves at the conversation pace; quiet types get steamrolled, and the city won't slow down for them.