Exploring the area west of Santander feels like being in a time machine. Within a half-hour drive of the Cantabrian capital on Spain’s green northern coast, you can stumble upon prehistoric cave art, a perfectly preserved medieval town and a laid-back beach resort.

When I began my weekend trip, it was raining, so my journey started in the Upper Paleolithic period, at the Cave of Altamira, a Unesco world heritage site, staring up at some of the oldest art on Earth. Well, almost. The original cave was largely closed to the public decades ago to protect the fragile paintings, so we were inside the Neocueva, a painstakingly reconstructed replica built beside it that costs just €3 to enter.

Above me, bison and deer charged across the undulating rock ceiling, their bodies rendered in rich ochres and charcoals. The prehistoric artists who painted them – hunter-gatherers who lived here 13,000 to 36,000 years ago – used the natural bumps and hollows of the cave to give the animals a three-dimensional presence.

Altamira is often called the Sistine Chapel of prehistoric art, and standing beneath those larger-than-expected painted animals, it’s easy to see why. Knowing the paintings were replicas did little to blunt their impact.

The cave, whose main entrance was sealed around 13,000 years ago by rockfall, was discovered in 1868 by a local hunter and brought to wider attention by amateur archaeologist Marcelino Sanz de Sautuola. When, in 1880, Sautuola first presented the paintings to the scientific community, many experts dismissed them as fakes, unable to believe that prehistoric people were capable of such sophisticated artistry.

Walking through the museum, it’s striking how little humanity has changed. From handprints pressed against cave walls to the selfies visitors take beside them today, the impulse is the same – to leave a trace.

Time was slipping away and my travel companions – my husband and our infant son – were beginning to lose patience with my archaeological enthusiasm. Hungry and still slightly awestruck, we drove a few minutes down the road to Santillana del Mar, the small medieval town that serves as Altamira’s gateway.

After a quick lunch, we found ourselves in the middle ages. Santillana del Mar feels as though it’s come straight from the pages of a fairytale or, for the less imaginative among us, Game of Thrones. Nobles’ houses, monastery buildings and towers line winding cobbled streets. At this point, the rain turned out to be something of a gift, emptying the streets of tourists.

Santillana traces its origins back to the ninth century, when monks carrying the relics of Saint Juliana settled here and built a small hermitage. Around it grew a monastery, then homes, farms and workshops, forming a settlement that gradually evolved into Santillana. During the middle ages, the town flourished as part of the Astur-Leonese kingdom and became an important stop for pilgrims travelling along the Camino de Santiago.

The flow of travellers brought trade and wealth, hence the grand stone houses and palaces. In 1209, King Alfonso VIII granted the town a charter, the height of its medieval prosperity.

The town sits close to the start of the Camino Lebaniego, a less well-known pilgrimage route that winds inland to the monastery of Santo Toribio de Liébana in the Picos de Europa mountains. Cantabria is the only region in the world crossed by two Christian pilgrimage routes recognised as Unesco world heritage sites.

For a town deeply tied to Christian pilgrimage, it is perhaps unexpected that Santillana is also linked to existential philosophy. In 1935, Jean-Paul Sartre visited the town with Simone de Beauvoir. A few years later, Santillana appeared in Nausea, Sartre’s first novel, as the narrator points to a photograph and describes it as “the prettiest town in Spain” during a conversation about the nature of adventure.

“Getting on the wrong train. Stopping in an unknown city. Losing your briefcase, being arrested by mistake, spending the night in prison,” says the Self-Taught Man. “Monsieur, I believed the word adventure could be defined: an event out of the ordinary without being necessarily extraordinary.”

By that definition, my own adventure was well under way.

Travelling through medieval streets with an infant is not for the faint of heart. Umbrella in one hand and baby carrier in the other, we trudged through the rain and our son fell asleep – ruining his nap schedule and our chance of an afternoon rest.

Still, Santillana has a way of softening such moments. We ducked into the Casa Quevedo bakery, where the same family has served fresh milk and cakes since the 1950s. Inside the medieval building, a glass of milk felt like the perfect antidote to grey skies and parental exhaustion.

From Santillana, it’s a 10-minute drive to the seaside town of Suances, our final stop – and another lurch of the time machine. Driving past the main part of town and towards the more touristy area of the coast, apartment blocks and seaside hotels appeared in pastel shades. We checked into Costa Esmeralda Suites, a five-star hotel offering generous off-season discounts. On the outside, it resembles a traditional mansion. Inside, however, the design feels like a time capsule of turn-of-the-millennium luxury: red carpets, a Ferrari-theme and enormous whirlpools.

Just a short walk away lies Playa de la Concha, where Atlantic waves roll towards wide sandy dunes. The rain finally eased as we arrived.

Near the port, restaurants and cafes buzzed with activity. “Other surf towns in the area are dead in winter,” one resident, Inma, told me in the Marcelo Gourmet bar and restaurant. “But Suances is always full of life.”

Out of summer, wetsuited surfers paddle out into the surf, sometimes with views of the snow-capped Picos de Europa mountains behind them. And the food alone is reason enough to visit. At Bonito Verde, we ordered a plate of rabas (fried calamari, a local speciality), so fresh and crisp they disappeared almost instantly, along with delicious squid-ink croquetas. Curiosity also led us to Suka, an unassuming restaurant rumoured to serve some of the best sushi in Cantabria. It was another win.

For breakfast, locals pointed us to Castillo de Los Locos, which houses a restaurant perched dramatically above the cliffs of Playa de Los Locos, and where the food is good and the views are incredible.

The last morning, I woke early and slipped out of the hotel room, leaving my sleeping family behind. Sunlight had finally broken through the clouds. I walked along the thin peninsula that juts out between Playa de Los Locos and La Concha, listening to birdsong and watching waves crash against the cliffs. It’s only a short walk beyond the Castillo de Los Locos, but it felt far from civilisation.

Standing there, breathing the salt air and feeling the sun, I relaxed.

After singing the praises of Santillana, Sartre’s Nausea protagonist reflects that adventure isn’t something we can experience while it’s happening. Instead, he says, adventures are made after the fact, by looking back and turning experiences into stories. “But you have to choose,” he continues. “Live or tell.”