As we hit Jane Jacob’s 101^st birthday this year (which coincides with Preservation Month), it’s fitting that we take a moment to think not only about why her theories have influenced city planning and preservation for decades, but how she came to form them in the first place.

Jacobs had no formal training in urban planning, nor was she an architect, or even a self-proclaimed preservationist. But today preservationists and urbanists alike recognize the significance of her ideology—what works and what doesn’t—and how it continues to shape our cities.

Preservation Month is the perfect time to think about the places that matter to us, and why. So we’ve come up with a few words of wisdom from Jacobs to help you think more like her, long after May is over.

1. “While you are looking, you might as well also listen, linger, and think about what you see.”

Jacobs moved from Scranton, Pennsylvania, to New York City to become a journalist. When she was working for Architectural Forum, she was assigned to the city-planning beat, about which she knew nothing.

So, she educated herself. She would walk or ride her bike all around Manhattan, asking questions about the city’s planners: What were their goals? Were they successful? If they failed, why? Jacobs searched for answers on what made a city a place that people could live in and be happy.

2. “Cities have the capability of providing something for everybody, only because, and only when, they are created by everybody.”

Jacobs believed that the problem with city planners of the preceding century—and with her contemporaries—was that they planned for the short term and without much input from the people who would be affected. She advocated for a bottom-up approach to ensure that people living in cities would be able to shape (and love) where they live.

3. “When we deal with cities we are dealing with life at its most complex and intense. Because this is so, there is a basic esthetic limitation on what can be done with cities: a city cannot be a work of art.”

Jacobs knew city life was “chaos,” but the good kind. Cities and city neighborhoods thrive when they can develop naturally, with the people who live there making that change happen. Appreciating the natural order of neighborhood life was, to Jacobs, the key to creating robust cities.

4. “The point of cities is multiplicity of choice.”

Jacobs believed a city thrived when people had options, specifically in transportation. If a person has the choice to either walk or take the bus, they will choose the option that best fits their needs, and that may change week to week.

Overall, she preferred pedestrian traffic over automobile traffic. Jacobs saw in her own neighborhood, Greenwich Village, that wide sidewalks and pedestrian-friendly blocks that encouraged walking would create a more vibrant and thriving city because people and neighborhoods would not be so isolated.

5. “Intricate minglings of different uses in cites are not a form of chaos. On the contrary, they represent a complex and highly developed form of order.”

According to Jacobs, the city is an ecosystem. The most basic ecosystem relies on varied interactions of living and non-living organisms that alone could not survive. It is only when all parts of an ecosystem connect and overlap that each part contributes to a whole.

When the interacting components of cities are divided, a city cannot thrive. A city with a designated shopping district, for example, creates a lonely and potentially unsafe part of the city after dinner time, when the shops close and few people remain. A strictly residential neighborhood has a familiar pattern in which people’s habits (sleeping, going to work, coming home, etc.) create a monotonous and predictable cycle that rarely varies. This doesn’t create a thriving city. It encourages separation and dulls city life.

Cities need blocks of mixed-use communities and neighborhoods that naturally create a sustainable city ecosystem.

6. “Old ideas can sometimes use new buildings. New ideas must use old buildings.”

Old buildings are crucial to thriving cities. Jacobs was a fan of using existing over new buildings whenever possible. She knew cities needed diversity not only in its people and businesses, but also in its buildings.

Today, we at the National Trust work to build upon Jacobs’ ideas for today, championing for adaptive reuse of older buildings. As she saw, maintaining and reusing existing building stock in cities often leads to positive change, including more people, more entrepreneurial activity, and thus more diversity.

7. “Streets and their sidewalks—the main public places of a city—are its most vital organs.”

Jacobs used a bottom-up approach to view the city and determine how to make cities work. At the core of her message were the street and its sidewalks. She liked short blocks with a multitude of different businesses, attractions, and housing that fostered community and visual diversity.