Later, in the U.K., where he established his own firm, Rogers was asked by a New Labour government to chair an urban task force, to try to stanch sprawl and lure people back to the core of cities. The commission’s report, released in 1999 and called “Toward an Urban Renaissance,” looks like a blueprint for cities everywhere in the last 20 years: it recommended creating greater density with infill construction, particularly on brownfield sites; improving public transit and public spaces; encouraging amenities such as shops, outdoor markets, and cafés, to spark street life—an urban approach that Rogers could trace, like the piazza of the Pompidou, to his Italian roots (he was born in Florence). According to the Guardian, housing density and brownfield reclamation increased significantly as a result. Rogers also crafted proposals specific to London, such as congestion pricing to ease traffic, under an appointment by the mayor.

His critique of modern cities and his remedies aimed at sustainability were codified in his 1995 book, edited by Philip Gumuchdjian, Cities for a Small Planet. (You can indeed tell something about it by its cover: like Rogers’s famously colorful shirts and socks, it is hot pink with the title in bright green.)

Rogers’s plans for more compact, livable cities were sweeping, but one of his visionary contemporaries, the architect Oriol Bohigas, took the opposite tack. Named planner of Barcelona in 1980, as the city was emerging, broke, from the long shadow of Franco’s nearly four decades of dictatorship, Bohigas hit on a brilliant idea for micro-interventions. Pairing an artist with a local architect (and Barcelona was full of great designers, little known at that time outside Spain), these duos created piazzas in outer neighborhoods that were blighted by soulless apartment blocks from the Franco era, with little or no public space. Major sculptors—such as Richard Serra and Beverly Pepper (each receiving a modest fee)—began to join the program as it grew in stature. Ultimately, more than 100 such places were built, most of them in parts of the city that tourists rarely visit. Bohigas, who died at age 95 at the end of November, had ignored Daniel Burnham’s dictum, “Make no little plans”—and, in fact, he had shelved a master plan, early on, as undemocratic. His genius was in understanding the impact that seemingly small projects could have on ordinary people and the real life of the city. The plaza program brought him international acclaim, as did his presiding over reshaping parts of Barcelona for the 1992 Olympics and beyond.

Each of these figures, in his own way, was a humanist, and each left a trail of ideas for those in the next generations to consider, adapt, or take in new directions.