“Shhh. Let’s try to keep quiet,” said my guide, Saša Šimpraga, as he pushed open the weighty wooden door of the Arnold, a late-19th-century apartment building in Zagreb’s city centre. The silence inside was a stark contrast to the noise of rush hour traffic on the street.

We silently crept across the hallway’s mosaic-tiled floors and slipped into the residents-only courtyard in the back. There, behind moss-topped stone columns and wrought ironwork, two lofty gingko trees soared over the remains of a weathered gazebo. It was a parallel realm of peace and quiet, in the city where I was born and raised.

“I don’t use any transport but my own feet and when I see an opportunity, I enter unlocked buildings to see what’s in the back,” explained Šimpraga, founder of 1percentforthecity, a volunteer group that lobbies the city government for urban works such as new and revived public parks.

To raise awareness about Zagreb’s hidden spaces, Šimpraga offers curated guided walks – “urban explorations”, as he calls them – for friends of friends and curious visitors; the only form of payment he’ll accept is a book from his wish list. Considering his vast local knowledge of Zagreb’s lesser-seen side, I asked Šimpraga to take me off the main streets and into often overlooked city corners, on a hunt for some of Zagreb’s secret courtyards, a feature of the city unknown to most locals – including me.

In Zagreb, every courtyard has a story. This was the slogan of Dvorišta, the tourism board-backed pilot project that drew more than 30,000 visitors to the city’s medieval Upper Town last summer. For 10 consecutive evenings, four baroque palaces and historic townhouses opened their private courtyards and gardens to the public for music, food and community gatherings. The upcoming instalment of Dvorišta, slated for 17 to 26 July this year, promises to showcase an even richer repertoire, with classical and jazz concerts and access to more off-limits courtyards than the year before.

Traced back to late-19th-century city planning, Zagreb’s courtyards were originally created as private, sometimes verdant spaces for use by the residents of the city blocks surrounding them. As time passed, however, many were forgotten. Buildings’ street-facing facades were beautified while out-of-sight veže (courtyards) became turned into parking lots and private workshop areas. But today, many of Zagreb’s courtyards are getting a new lease on life as local entrepreneurs start to see their potential. And these previously overlooked corners are where some of the city’s most remarkable life unfolds, away from well-trampled routes.

Take Cafe u Dvorištu, which translates literally as “cafe in the courtyard”. Most people would never naturally swerve off the leafy thoroughfare known to locals as “the green wave” (for its street lights that turn green simultaneously). But those who do take notice of the arched passageway, marked only by a subtle sign, will find a courtyard café whose backstory belies its surroundings.

This low-rise building has had several lives: first as a light bulb factory in the 1940s, then as a music store. Four years ago, the space was taken over by a couple who met in the United States – Matija Belković from Zagreb was studying philosophy in Boston when he met his wife Hannah Powlison from Philadelphia. Together, they’ve created one of Zagreb’s most spirited culture hubs. The dimly-lit space is full of mismatched chairs and tables made of stacked suitcases, sitting on scruffy Persian carpets.

In the glass-separated room next door to the café, Belković runs Cogito Coffee Roasters in partnership with Matija Hrkać, one of the region’s best baristas. All coffee is roasted in situ, including their seasonal Tesla Blend Light. At the time of writing, the blend featured beans from Brazil, Honduras and Ethiopia.

The combo cafe-cum-roaster space hosts events such as literary readings and on warm days, food and craft fairs outside. “It’s the courtyard itself that motivates us,” Belković said, “We’re part of a larger story, giving life to disused spaces around Zagreb.”

A courtyard on Jurišićeva – a street I pass daily – houses LiberSpace, a haustor-gallery (haustor is another Croatian word for courtyard) that hosts installations by local and international artists. One such piece was an audio work by artist Tanja Vujasinović, which played back the sounds the artist recorded in the very same courtyard during the day.

Zagreb’s courtyards also hide some of the city’s tastiest food. Less than 1km east of Trg Bana Jelačića, Zagreb’s main square, a courtyard conceals the miniature Mali Bar, which serves up a menu of culinary fusion – think Japanese fried chicken and smoked octopus pasta – under the helm of Ana Ugarković, a renowned cookbook author and television personality. In the same courtyard, Karijola is a pizzeria with an open-air terrace, featuring pizzas with unusual toppings such as fennel, shiitake mushrooms and gorgonzola. One of Zagreb’s top vegetarian spots also hides away in a city centre courtyard: Zrno, in a courtyard off Medulićeva street, is a sleek bistro that does a fantastic seitan cordon blu.

On my stroll with Šimpraga, we popped into an ordinary-looking courtyard on Jurišićeva, near where it intersects with Draškovićeva, and found an enchanting rooftop garden sitting above a vacant bungalow-style building, the foliage just barely viewable at street-level. At #34 Ilica, Šimpraga steered me through the passageway, past a sign at the bottom of the staircase that said “The garden isn’t a public space!” and up a set of stairs. In front of us stretched a small park with an aged stone fountain backed by a verdant view of Zagreb’s Upper Town.

While the Dvorišta initiative has certainly made such hidden spaces more accessible to the general public, it didn’t feel like enough. Looking out on the garden in front of me, I couldn’t help wishing that these spaces weren’t, for the most part, withheld from the public eye. To this critique, Šimpraga had a ready counterpoint: “If you had a space like this, would you open it up?”