Alicia Pederson went from a Renaissance literature PhD and a two-year stint as an au pair in Florence to becoming one of the best voices on a deceptively simple idea: the courtyard in the middle of apartments.

After watching family friends priced out of Chicago one by one - not because they disliked the city, but because the only family housing on offer was a million-dollar house with a private yard - she started asking why North America builds apartments as huge, hotel-like buildings when European cities solved this centuries ago. Her answer is the courtyard block with apartments that live like houses, with a front door onto the street and a back door onto a shared green courtyard. It's a housing idea that's genuinely lovable, demonstrably doable and cheaper to build ... and, as we get into, almost entirely illegal to build in many North  ...