The 19 coolest, most overlooked places for a summer holiday in Europe

Globetrotters are always looking for new, under-the-radar travel destinations that provide a chance to escape the crowds and sea of selfie sticks.

As summer kicks off, Business Insider asked friends, colleagues, and some of the world's top travel experts for their favourite — and most overlooked — European destinations that can be seen in a long weekend.

From the mystical Arabic influence of Granada to the dilapidated charm of Porto and the gothic churches of Transylvania, here's a selection of their top recommendations, along with some local tips.

Pretend you're in a Bond film at the Bay of Kotor, Montenegro.

Montenegro provides a less obvious alternative to neighbouring Croatia, and it's not hard to see the draw of the stunning setting of the Bay of Kotor, with its glistening Adriatic sea and mountainous backdrop. The bay is also home to the preserved medieval old city of Kotor which just so happens to be a UNESCO World Heritage site.

One TripAdvisor user from the UK called it "Europe's best kept secret."

"Despite seeing many images of this place before my visit, nothing really prepared me for just how stunningly beautiful this bay is," the review stated. "The waterside setting (obviously) with its mountainous backdrop was for me a cross between the Norwegian fjords and those lovely Alpine lakes."

Admire the azulejos (painted tiles) and dilapidated charm of Porto, Portugal.

Emma McWhinney, the UK head of editorial at Secret Escapes, recommends a long weekend in Porto, a coastal city on Portugal's northern coast that's steadily growing in popularity as an alternative — possibly even a cheaper one — to Lisbon.

"Often overshadowed by bustling Lisbon, Porto, with its coastal thrills, postcard-perfect architecture, and eclectic culinary scene, is a must-visit cluster of colour and charm," she said.

Wander through Porto's hilly streets and admire the crumbling buildings and ramshackle colourful houses decorated with azulejos (painted tiles), and you'll soon see why its dilapidated charm is drawing in tourists.

Porto's proximity to some pretty stretches of beach adds to its appeal.

Soak up the Andalusian sunshine, snack on the famous free tapas, and lose yourself in a colourful maze of market stalls in Granada, Spain.

Granada, located in Spain's southern Andalusian region, is a city rich in history and culture —and its Arab influence gives it a mystical edge.

Aside from the tapas — it's one of the few places in Spain where a free tapa is religiously served with every drink — there's the majestic Alhambra Palace, abundant Arab baths that make a perfect first stop to unwind into your weekend, and the intriguing whitewashed gypsy caves of Sacromonte, where some of the city's best flamenco haunts lie.

Sakshi, a New York-based editor who recently visited the city, told Business Insider: "We enjoyed one free tapa with each drink. So we bar hopped as is recommended, we didn't ever get a second round at the same place.

"A tip for tourists is saying 'que tapa' after letting the bartender know the intention is a drink — either a cana (a small beer) or copa (little glass of wine). Bar Bodegas Castañeda came highly recommended and is somewhat of an institution. We started our bar hop there," she added.

Admire the sun-drenched domes and rooftops of the old town over sundowners in Cagliari, Sardinia.

While many flock to the glitz and glamour of northern Sardinia to enjoy the crystalline waters of the Costa Esmeralda, those wanting their money to go further should consider the south, specifically the island's capital of Cagliari, where I recently enjoyed a spectacular city break.

Perched on a hilltop, Cagliari's historic centre Castello provides the perfect spot from where to admire the sun-drenched domes and rooftops of the old town over sundowners.

After a long day of sightseeing, a particularly nice spot for an aperitif is the giant terrace at Caffè delle Art i which offers stunning panoramic views of the city and a good selection of craft beers the size of wine bottles.

The velvety local red wine, Cannonau, is not to be missed. Equally as enjoyable is the house red served chilled in jugs at restaurants — both slip down all too quickly.

Have an idle afternoon sunbathing on rocks or watching fishermen untangle their nets in Rovinj, Croatia.

Jess Cole, features editor for Lonely Planet magazine, picked Rovinj in Croatia as a perfect spot for a weekend break.

"With its piazzas, pastel-coloured townhouses, and elegant belltower, it's no surprise that the dignified Croatian town of Rovinj was once a subject of the Venetians," she said.

"Sights here are relatively few - the chief activity being myriad forms of relaxing by the sea. Idle away an afternoon by a quayside cafe watching fishermen untangle their nets, or stroll the cypress-shaded park of Zlatni Rt."

Enjoy lunch and unlimited cider at one of San Sebastián's cider houses.

San Sebastián, a seaside resort on the Bay of Biscay in Spain, is perhaps best known for its traditional Basque country tapas called "pintxos." Max, a primary school teacher from London, also recommends its cider halls, or "sidrerías," where she explained reservations are made at tables by laying a baguette across them.

The cider houses serve food, too. You can enjoy a set menu that typically includes dishes like salt cod omelette, fish, steak and a dessert of cheese with walnuts and sweet biscuits, according to TripAdvisor users, alongside unlimited cider, of course.

Marvel at the ancient ruins and indulge in the local coffee culture in trendy Athens, Greece.

James McClure, Airbnb's general manager for Northern Europe, suggests a trip to Athens this summer.

"Athens is more than just a gateway to the Greek islands; it's fast becoming popular amongst millennials thanks to the growing number of coffee shops, rooftop bars, and unique accommodation, including this luxury loft and sci-fi penthouse on Airbnb, all set against the city's ancient monuments."

Couleur Locale, a rooftop near Monastiraki which offers stunning views of the Acropolis, is popular with hipster locals and tourists alike. TripAdvisor usersnoted its particularly good cocktails, and say it works just as well for brunch or evening drinks.

Eat proper Italian pizza in Naples, Italy.

McClure says Naples is also worthy of a long weekend. "While its contemporary art scene is growing in momentum, visitors to the city can experience the juxtaposition between old and new by exploring the nearby Roman town of Pompeii or learning about traditional cooking on the Amalfi Coast."

It's a lot cheaper to stay in Naples than the likes of Positano, too.

But the city's biggest draw is obvious. According to Laura, an operations officer from London who recently visited, a must-see is the world-famous L'Antica Pizzeria da Michele.

"There's only two types of pizza to choose from — Margarita and Marinara — and for only 4 euros each," she told Business Insider.

Travel back in time wandering the medieval citadel town of Sighisoara in Transylvania.

If you're looking for something truly off-the-beaten-path and cobbled streets and gothic churches are your thing, Alex, a financial journalist based in London, recommends a visit to the depths of Transylvania, specifically Sighisoara and Brasov.

"It feels fairly adventurous going there as there are few tourists and it's amazingly cheap to stay in the best hotels you can find," she told Business Insider.

"Sighisoara is like going back in time — a beautifully preserved medieval citadel town. Meanwhile Brasov is bigger and a highlight was going for a guided hike in the mountains and national park nearby, which are beautiful and still have many bears and wolves in the wild. There's also a sanctuary for rescued bears."

The 13th century Bran "Dracula" Castle (pictured above) is also well worth a visit, she says. Prince Charles happens to be a big fan of the region, too, and even owns houses there.

Take Instagram-worthy snaps of the purple lavender and turquoise waters of the Calanques in Provence, southern France.

Supping on the local rosé is just one of the many draws of Provence, southern France, along with incredible coastline, extremely 'grammable lavender fields, and the stunning city of Aix-en-Provence. It was also just named among Lonely Planet's top 10 European destinations for 2018.

According to TripAdvisor users, you should take a boat ride to the Calanques, the rocky inlets of its coast, to swim in the turquoise waters.

Discover the fairytale-like setting of Lake Bled.

Travel experts at search platform HolidayPirates suggested Ljubljana, the capital of Slovenia, for a less obvious city break this summer. It's under an hour's drive from there to the country's standout attraction that is the fairytale-like setting of Lake Bled.

According to Slovenia's tourist board, you should take the traditional wooden "pletna" boats out on the blue waters to visit "Bled Island," and climb the 99 stone steps to reach the Assumption of Mary Church.

Get giddy on fresh rock oysters in Whitstable, England.

Ali Millington, senior editor at Business Insider UK, suggests a trip to Whitstable, Kent.

"Whitstable is a charming seaside town that's about an hour's train ride from London, making it doable for a weekend or even just a day. If you're a fan of seafood — and quaint fishermen's huts — this is the dream break.

"Be sure to head to Wheelers Oyster Bar, whether it's for the oysters themselves, the succulent lobster, or the Instagram-worthy facade," she added.

Be warned, you must call ahead — this tiny restaurant gets booked up well in advance, but it's worth it even if you're sat at the counter. To top it off, it's bring your own booze (BYOB).

Take in the pops of colour in Tirana, Albania.

Neil Cartwright, a travel expert at Kayak, suggests a visit to Tirana, Albania.

"Albania is one of the lesser-known European countries, but one that is great to visit for a long weekend. Tirana has changed a lot over the years and is a great city with lots of culture, entertainment, and an interesting political centre," he said.

"It's a city full of colour so is great for populating your social channels!"

Enjoy the stunning beaches and tuck into a Michelin-starred meal in Jersey, Channel Islands.

Millington recommends a trip to Jersey, too.

"It may be a bit sleepy off season, but Jersey — the largest of the Channel Islands which is just a 55 minute flight from London with BA — is home to some stunning beaches and an incredible Michelin-starred restaurant, Bohemia, making it the perfect relaxing weekend break."

Boat down the Garonne in France's wine capital, Bordeaux.

Instead of Paris or Lyon, head to Bordeaux, France's wine capital, where there's more to discover than just a fine glass of red, according to Airbnb's McClure.

"A direct train between London and Bordeaux is in the pipeline and I'm not surprised," he said, adding that highlights include exploring the city's famous bridges by boat along the Garonne and taking a wine tour to one of the many surrounding vineyards, where you can learn about the special features of the best Bordeaux wines, soils, and aging tools.

The city boasts a thriving art and foodie scene, too.

Turn to Brno for an alternative to Prague, where you won't have to see through a forest of selfie sticks.