Top five: The best international cities for solo travellers

There's no shortage of extraordinary strolls here - from eye-popping window-shopping on Fifth Avenue to the must-do High Line, where you can catch a slice of local life. Just don't forget to have a drink at one of the city's many piano bars, such as Marie's Crisis Cafe where you can often spot guests playing the piano, before other regular punters join in for a singalong, and soon you realise they're all either wannabe or established Broadway stars. nyctourism.com

If the technicolour hues of this Portuguese city don't leave you mesmerised, its happening neighbourhoods will surely do the trick. Start your explorations at Sao Jorge Castle - a historic landmark from where you can soak up bird's-eye views of the city, complete with its vivid rust-red roofs.

Then venture into some of its hottest nooks - wander through the narrow cobbled streets of Alfama and have a drink at a traditional fado music house, or visit the bohemian Bairro Alto, which is home to some of the city's trendiest bars and its most famous funicular, Bica. And for your fill of pasteis de nata (the traditional Portuguese custard tarts), make a beeline for Pasteis de Belem, which is considered to be the birthplace of this delicacy and still follows a secret recipe, drawing endless queues. visitlisboa.com

When it's sunny and balmy, there's no place quite like the British capital, where locals claim every square inch of open spaces as mercury rises. Parks, river banks, historic squares and even the steps of St Paul's Cathedral throng with crowds. Soak up the magic with a stroll down Regent Street, where gorgeous Georgian and neoclassical architecture meets some of the world's best show windows. Then make your way to Old Compton Street, where crowds burst out of old crusty pubs and cram the streets with beer-spilling jolliness.

In fact, even when it's cloudy and cold, there's no place like the British capital. Lose track of time at the National Gallery among masterpieces by van Gogh, da Vinci and Rembrandt. Or head to the original Madame Tussauds museum to go face to face with life-sized statues of famous people - all the way from Churchill and Princess Dianna to Usain Bolt and Beyonce. visitlondon.com

There's a giant stainless steel flower - about seven storeys high - in a park in Buenos Aires. It's meant to unfurl during the day and fold up at night. But it doesn't always work. And that pretty much sums up the sultry Argentine capital, where things don't always go to plan. Particularly, when you're exploring colourful neighbourhoods such as La Boca and San Telma, where attractive dancers break into a tango at the drop of a ... sombrero.

Explore the buzzing streets by day at your own pace and without agenda. By night, though, don't forget to check out the city's "closed door" scene: drinking and dining dens that are hidden behind, say, a flower shop, such as Floreria Atlantico, currently number 46 on the World's 50 Best Bars list. turismo.buenosaires.gob.ar

Read more on Explore:

The capital of Vietnam is a hypnotic blend of the old and the new. Check in to Sofitel Legend Metropole Hanoi, which - dating back to 1901 - is steeped in legend, yet offers cutting-edge comforts: from a world-class spa to the ravishing Angelina cocktail bar. Then explore the Old Quarter on foot - ideally first thing in the morning when you can feel the city stir to life: priests opening the gates of centuries-old temples, elderly women line dancing on the banks of a lake and vendors selling all sorts of foods - from prime cuts of meat to banh mis - setting up their stalls.

And make sure you time your visit to coincide with a weekend, when the entire Old Quarter of Hanoi is transformed into a pedestrianised zone, making a solo aimless wander through the city one of the most evocative experiences. vietnam.travel