We began the Steps for Sustainability in Lisbon, seeking inspiration from street artists on how to reimagine cities. Our next step takes us to Turin and Houston, two cities whose pasts are influential in defining their paths toward a post-carbon future.

The city, however, does not tell its past, but contains it like the lines of a hand, written in the corners of the streets, the gratings of the windows, the banisters of the steps, the antennae of the lightning rods, the poles of the flags, every segment marked in turn with scratches, indentations, scrolls.- Italo Calvino, Invisible Cities

Italo Calvino had already skipped out on Turin, a city that “entices a writer towards vigor, linearity, style,” he once wrote, trading it for that “enormous cheese encyclopedia,” Paris, when he published Invisible Cities, a work that has inspired students of urban theory, landscape architecture, and comparative literature. The passage above comes from his description of Zaira, a point where memory meets its climax and desire begins to redraw the boundaries of possibility. Calvino understood that a city’s history, real or perceived, inspires its future, and that this history is found in the objects scattered along the streets. Imagination and interpretation become the axes on which the potentialities of cities are mapped.

So how can we apply Calvino’s insights to developing the post-carbon cities of tomorrow? Working backward to move forward, we can begin with a map, walking the streets and parks to discover a city’s story and reimagine its future. Or, if we don’t have a map, we can seek out a reliable guide—someone like Pedestrian Pete.

Blame it on Gary Cooper, John Wayne, or the whole Western film genre, but Texas is famous for walking—or rambling, sauntering, and strolling. So why does Houston make it so hard? In that sense, Pedestrian Pete is not just continuing a great tradition; he’s rescuing it. The alter ego of Peter Brown, founder and director of BetterHouston and former member of the Houston city council, has made it his mission to walk the streets of Houston, a notorious oasis of car dependence and urban sprawl, encouraging his fellow Houstonians to get out of the tunnels (really) and onto the streets to meet their neighbors and reawaken their neighborhoods.

Pedestrian Pete knows it’s not quite that simple. So he’s targeted his advocacy a bit—city officials, those with power and responsibility to make sure telephone poles don’t block wheelchair access to sidewalk ramps and who can ensure that new city developments support the environmental, health, and safety benefits—not to mention the multitude of studies showing the economic advantages—of walkable urbanism. Now, with a growing group of loyal followers and a new column for the local alternative paper Free Press Houston, the city might be on the cusp of an epic confrontation between its gas-guzzling past and a post-carbon future: High Noon, Pedestrian Pete-style.

Turin, too, is looking for ways to make its city center more pedestrian friendly. In April 2015, after a somewhat contentious trial period, the city government approved a measure making a marquee stretch of Via Roma car free. Lined with marble columns and high-end boutiques, Via Roma is as much a monument to Turin’s sumptuous history as it is a cosmopolitan center of commerce. Car-free advocacy in Turin is met with much the same resistance as in Houston. Turin put the ‘T’ in the now Dutch-British-NYSE-listed Fiat and is still considered Italy’s car city. Driving is not just a rite of passage; it’s an acknowledgment of the economic and cultural power of the car industry. Names like Bertone and Lancia have helped write the story of Turin, and it isn’t necessary to erase those names (as if it were possible) from the city’s post-carbon future. In fact, heading north of the city center, we see Turin’s industrial past shaping sustainable urbanism.

For over a century along the Dora Riparia—Turin’s other river—a constant buzz, not to mention a few grey clouds, dominated the atmosphere, a collateral consequence of the factories of hometown icons Fiat, Michelin, and Savigliano. Today the buzz is more likely to come from a music festival, an Eid al-Fitr celebration, or Torino Bike Pride; the clouds from street food vendors or fireworks. The 456,000 square meters (more than 112 acres) of abandoned manufacturing plants have been replaced by community gardens, green spaces, skate parks, concert stages, bike trails, and even a swimming hole—all the while keeping alive the ghosts of the industrial wasteland.

The process of creating Parco Dora, a post-industrial urban paradise, began at the turn of the century. After an international call for applications, a group of architects, engineers, artists, and consultants, including the landscape architect responsible for this impressive reincarnation, went to work. But the real mark of success began in May 2011, when the first sections of Parco Dora opened and the city’s citizens began integrating it into their daily lives. Another section followed in 2012, and work continues, transforming the city’s industrial past into a landmark of contemporary sustainable urbanism.

Like Turin, Houston’s taken a new look at the vestiges of its history, and not just the built kind. Houston is the Bayou City. If you aren’t familiar with bayous, here’s a great primer, but basically they are long, meandering not-quite-rivers, and Houston has a lot of them—about 2,500 miles, in fact. For decades, developers and engineers worked to pave the bayous in hopes of driving flood waters away. Luckily, the city has changed direction (as bayous, too, are at times wont to do), promoting the bayous as optimal recreation opportunities—just don’t drink the water.

But an ambitious, long-term initiative, Bayou Greenways, goes a step further. Bringing together private and public resources to create 4,000 acres of green space and more than 300 miles of continuous bike trails, this Texas-sized development project is turning the sprawling entirety of Houston into a park. Not only do the Bayou Greenways soak up CO₂ emissions and improve water quality, they will connect the city’s disparate neighborhoods, making the natural history of Houston a vital part of its post-carbon future.

The city contains its past, as Calvino wrote. That I agree with. But after visiting the walkable streets and urban gardens, greenways and skate parks, like those we’ve just seen in Turin and Houston, it seems that within that past, if we get the story right, we can find the city’s sustainable future. All we need to do is take a walk.