Set on a plain rising gently from the sea to a range of wooded hills, Barcelona is Spain’s most cosmopolitan city and one of the Mediterranean’s busiest ports.

Set on a plain rising gently from the sea to a range of wooded hills, Barcelona is the most cosmopolitan city in Spain, and one of the Mediterranean’s busiest ports. Restaurants, bars and clubs are always packed, as is the seaside in summer.

Barcelona has been breaking ground in art, architecture and style since the late 19th Century. From the marvels of Modernisme to the modern wonders of today, the racing heart of Barcelona has barely skipped a beat. The city's avant-garde chefs whip up a storm that has even the French reaching for superlatives. The city itself could keep you occupied for weeks, but just outside are sandy beaches, Sitges and the Montserrat mountain range. Here are a handful of things you should raise to the top of your to-do list.

Scaling the dizzy heights of La Sagrada Família
It is Spain's most visited sight - and it isn't even finished! For many, that is part of the attraction. If you have been to Barcelona before, you have probably already visited Antoni Gaudí's La Sagrada Família church. But that was last time, wasn't it? A work in progress, it is never quite the same. Lifts and stairs allow you to ascend a tower of each facade and look down over the splendid work below and the city around it, and perhaps feel a breath of the heavenly inspiration that touched Gaudí.

La Rambla
By day and night, multitudes stream along this tree-lined pedestrian boulevard (flanked by two clogged traffic lanes), a stage for street performers (from flamenco dancers to fire-eaters and more human statues than you could knock over in one go), pickpockets, three-cups-and-a-ball tricksters and more. Rip-off pavement cafes, Australian pubs and newsstands bursting with porn add to the local colour. As day turns to night, streetwalkers of all persuasions come out to play at the lower end of the boulevard, and many out-of-towners become more vocal as they revel into the wee hours.

Admiring Catalonia's artistic heritage in the Museu Nacional d'art de Catalunya (MNAC)
The Museu Nacional d'Art de Catalunya is a one-stop immersion course on the world of (mostly) Catalan art, from medieval church frescoes to chairs designed by Gaudí. The highlight is the Romanesque art collection. In the 1920s, art historians combed hundreds of churches dotting the northern Catalan countryside. Inside they uncovered unprecedented treasures: remains of bright Romanesque frescoes, some dating back to the 11th and 12th centuries. To save them from further decay, many were removed to Barcelona, and today they can be admired in the re-created interiors of those churches.

Wandering the fragrant gardens of Montjuïc
Barcelona is one of the noisier cities in Europe, and there's no better antidote to the grinding decibel assault of traffic, road works, sirens and blaring music than a lazy day of strolling amid the beauty and serenity of soothing gardens, all the while gazing back on the urban madness below. A trip to Montjuïc is already a must for its many fine museums, but it's also worth coming here just for a wander to see the fantastic views over the wide blue sea from one of its several botanical gardens. There is no better spot in Barcelona for a snooze under a tree.

Marvelling at the many zany Modernista creations in L'Eixample
If there is a part of town where you should always keep an eye skyward, l'Eixample is it. As you wander the grid of streets, your eyes fall upon the splendid and whimsical facades of the countless buildings that Modernista architects raised in a few short decades around the turn of the 20th Century. The closer you look at many of them, the more intriguing detail they reveal.

Peering at Picasso's precocious genius
Five hefty, stone, Gothic-baroque mansions in a row on medieval Carrer de Montcada are today occupied by Barcelona's Museu Picasso. This is a rare voyage of discovery. If any proof was needed that Picasso had all the technical ability to turn out whatever he wanted, from giant canvases to whimsical self-portraits, you have it in abundance here.

Meditating on times past in the Església De Santa Maria Del Mar
The grand Gothic church of Our Lady of the Sea was blessed in 1384. As you admire this splendid feat of medieval construction, imagine the religious devotion of the city's porters, who spent a day each week carrying on their backs the stone required to build the church, trudging all the way from the royal quarries in Montjuïc. Their very blood is etched into the church's walls, and their memory lives on in reliefs of them on the main doors and stone carvings elsewhere in the church.

Falling under a spell in Park Güell
What a fine flop! What started in 1900 as the dream of a Barcelonian magnate, Eusebi Güell, for an English-style 'garden city' for the hoity-toity ended up as an enchanting public space. Alice in Wonderland would feel at home, as you're greeted by two gingerbread houses of soft brown stone, topped by curvaceous, creamy-looking roofs decorated in trencadís (broken-up ceramics). The great pillared hall (Sala Hipóstila) would have housed the garden city's market. Its roof is a grand viewing platform across the city, lined by the Banc de Trencadís, a delightful bench that snakes around its perimeter and is clad with candy-coloured ceramics.

Sitting on the edge of your seat at a Barça match
For the sports-minded, little can match the glory and spectacle of a football match at FC Barcelona's Camp Nou stadium, one of the biggest and best in the world. The athletic genius of players in one of Europe's greatest clubs (founded in 1899) will have you sitting on the edge of your seat - along with 100,000 other spectators - when the stadium fills for big clashes, like the derby with arch-rivals Real Madrid.

Musing on epic seafaring at the Museu Marítim
Climb aboard the life-sized replica of Don Juan of Austria's elaborately adorned 16th-century galley, and imagine life aboard this warship. Hundreds of men chained to the giant oars drove this vessel at up to nine knots. The cracking of whips; the agony of this mix of slaves, prisoners and desperate volunteers. The sheer stench. These wretches ate, slept and went to the toilet where they sat. You could smell a medieval galley from miles away. Don Juan's galley was launched here, at the Reials Drassanes (Royal Shipyards). The site has been a museum since the 1940s and is one of the most fascinating in the city.

The article 'Lonely Planet's top 10 sights of Barcelona' was published in partnership with Lonely Planet.