La Mercè 2018: Open doors

Monday 24, 10am-8pm.

Stretching from the Plaça del Rei to the cathedral are some 4,000sq m (43,000sq ft) of subterranean Roman excavations – streets, villas and storage vats for oil and wine, all discovered by accident in the late 1920s when a whole swath of the Gothic Quarter was dug up to make way for the central avenue of Via Laietana. The excavations continued until 1960; today, you can get to the labyrinth via the Casa Padellàs, a merchant's palace dating from 1498, which was laboriously moved from its original location in C/Mercaders to allow the construction of Via Laietana.

Monday 24, 10am-8pm.

One of the masterpieces of industrial Modernisme, this former yarn and textile factory was designed by Puig i Cadafalch and celebrated its centenary in 2011. It won the Annual Artistic Buildings Competition prize in 1913, but unfortunately spent most of the last century in a sorry state, briefly acting as a police barracks before falling into dereliction. Even in ruins, the building was declared a Historic Monument of National Interest in 1976. Now reconstructed and thriving, you'll find, in addition to the permanent contemporary art collection, three impressive spaces for temporary exhibitions – often among the most interesting shows to be found in the city.

Monday 24, 10am-8pm.

If you're used to being soft-soaped by eager-to-please art centres, you'll have to adjust to the cryptic minimalism of the Contemporary Art Museum of Barcelona (MACBA), where art is taken very seriously indeed. Yet if you can navigate the fridge-like interior of Richard Meier's enormous edifice, accept that much of the permanent collection is inaccessible to the uninitiated, tackle shows that flutter between the brilliant and baffling, and, most important, are prepared to do your reading, a trip to the MACBA can be extremely rewarding. Since its inauguration in 1995, the MACBA has transformed itself into a power player on the city's contemporary arts scene. Its bookshop is fantastic for quirky gifts and artist design objects.

Monday 24, 10am-3pm.

The highlight is the Romanesque collection. As art historians realised that scores of solitary tenth-century churches in the Pyrenees were falling into ruin – and with them, extraordinary Romanesque murals that had served to instruct villagers in the basics of the faith – the laborious task was begun of removing the murals from church apses. The display here features 21 mural sections in loose chronological order, including the tremendous 'Crist de Taüll', from the 12th-century church of Sant Climent de Taüll. Even 'graffiti' scratchings (probably by monks) of animals, crosses and labyrinths have been preserved.

Sunday 23 and Monday 24, 10am-7.30pm.

Even if you can't tell a caravel from a catamaran, the excellent Maritime Museum is worth a visit, as the soaring arches and vaults of the vast former 'drassanes' (shipyards) represent one the most perfectly preserved examples of civil Gothic architecture in Spain. In medieval times, the shipyards sat right on the water's edge and were used to dry-dock, repair and build vessels for the royal fleets. With the aid of an audio guide, the maps, mastheads, nautical instruments, multimedia displays and models show you how shipbuilding and navigation techniques have developed over the years.

Monday 24, 10am-7pm.

The construction of new access points for the 1992 Olympic Games facilities favoured the proposal to create a new botanical garden for the city. On Montjuïc, between the castle and the Olympic Stadium, the shape of the garden's 14 hectares is reminiscent of a great amphitheatre with preserved collections of Mediterranean plants worldwide and magnificent views over the Llobregat delta, the Olympic Ring and part of the metropolitan area of Barcelona.

Monday 24, 10am-3pm.

The Foundation boasts the most complete public collection of works by Joan Miró, made up of paintings, sculptures, pottery, textiles, engravings, and illustrations by the artist from all periods. Catalan architect and a great friend of Miró's, Josep Lluís Sert, designed one of the greatest museum buildings in the world, right there in a park on Montjuïc. This bank holiday weekend you can see the temporary exhibition 'Kader Attia. Scars Remind Us That Our Past Is Real'.

Monday 24, 10am-2pm.

Mies van der Rohe built the Pavelló Alemany (German Pavilion) for the 1929 International Exhibition not as a gallery but as a simple reception space, sparsely furnished with his trademark 'Barcelona Chair'. The pavilion was a founding monument of modern rationalist architecture, with its flowing floor plan and revolutionary use of materials. Although the original pavilion was demolished after the exhibition, a fine replica was built on the same site in 1986, the simplicity of its design setting off the warm tones of the marble, and the expressive Georg Kolbe sculpture in the pond.

Sunday 23, 10am-7pm & Monday 24, 10am-6pm.

Finally rehoused in the Auditori concert hall in 2007 after six years in hibernation, the Music Museum's collections comprise over 1,600 instruments, displayed like precious jewels in red-velvet and glass cases, along with multimedia displays, interactive exhibits and musical paraphernalia. With pieces spanning the ancient world to the modern day, and including instruments from all corners of the world, the museum's high note is the world-class collection of 17th-century guitars.

Monday 24, 11am-8pm.

Spain's largest cultural centre was opened in 1994 at the Casa de la Caritat, a former almshouse, built in 1802 on the site of a medieval monastery. The CCCB's exhibitions can lean toward heavy-handed didacticism, but there are occasional gems. There are also two large spaces for speakers, debates, and concerts. The most unique feature of this centre is the Xcèntric Archive, an archive for experimental films. The small 12-seat theatre is home to over 1,000 titles from prominent creators. Currently on at the CCCB is the recommended 'Black Light. Secret traditions in art since the 1950s'.

In 1326, the widowed Queen Elisenda of Montcada used her inheritance to buy this land and build a convent for the Poor Clare order of nuns, which she soon joined. The result is a jewel of Gothic architecture; an understated single-nave church with fine stained-glass windows and a beautiful three-storey 14th-century cloister. The place was out of bounds to the general public until 1983, when the nuns, a closed order, opened it up as a museum. The site offers a fascinating insight into life in a medieval convent, taking you through the kitchens, pharmacy and refectory, with its huge vaulted ceiling.

Monday 24, 11am-8pm.

Frederic Marès (1893-1991) 'collected' everything he laid his hands on, from hairbrushes to opera glasses and gargoyles. In 1944 he donated his collections to the city of Barcelona, and two years later this museum was inaugurated. Throughout his life, Marès amassed an extensive collection of Hispanic sculpture, from ancient times to the 19th century, dominated by polychromed carvings. The collection consists of tens of thousands of objects – some are everyday yet curious pieces such as fans, pipes, watches, jewellery and photographs – documenting how people lived and customs of the past, especially during the 19th century.

Monday 24, 9.30am-2.30pm

A UNESCO World Heritage Site, this former hospital is made up of 20 pavilions, abundantly adorned with the colourful Byzantine, Gothic and Moorish flourishes that characterise Catalan architect Lluís Domènech i Montaner’s style and set in peaceful gardens that spread over nine blocks in the north-east corner of the Eixample. The restoration has provided the starting point for an active cultural programme whose main objective is to further appreciation of this treasure of European Art Nouveau.

Monday 24, 10am-8pm.

The Military Museum closed down in 2009 and its contents were moved to Figueres. The castle is now an International Peace Centre. For now, visitors can stroll through the castle, climb the battlements for fabulous views, or picnic in the wide moat. There's a café in the Plaça de Armes.

Monday 24, 10am-8pm.

Said to be the biggest science museum in Europe, CosmoCaixa boasts excellent installations for children: the Planetarium pleases those aged five to eight, and the wonderful Clik (ages three to six) and Flash (seven to nine) introduce children to science through games. Toca Toca! ('Touch Touch') educates children on which animals and plants are safe and which to avoid. Some of the real highlights, for both young and old, are the hugely entertaining sound telescope outside on the Plaça de la Ciència and the amazing Flooded Forest room.

Monday 24, 10am-8pm.

Opened in 2007 in a new building across from the Olympic Stadium, the Olympic and Sports Museum gives an overview of the Games (and, indeed, all games) from Ancient Greece onwards. As well as photos and film footage of great sporting moments and heroes, there's an array of related objects (Ronaldinho's boots, Mika Häkkinen's Mercedes), along with a collection of opening ceremony costumes and Olympic torches. Perhaps more entertaining are the interactive displays, including one that compares your effort at the long jump with those of the pros.

Friday 21, Saturday 22 & Sunday 23, 10am-8pm.

This huge monolith, squatting at the side of Plaça de les Glòries, has housed the collections from the former museums of clothing, decorative arts and ceramics since it opened in December 2013. The Textile and Clothing Museum collection provides a chronological tour of fashion, from a man’s Coptic tunic from a seventh-century tomb through to Karl Lagerfeld’s creations. The Museum of Decorative Arts’ collection is informative and fun, and looks at the different styles informing the design of artefacts in Europe since the Middle Ages. A second section is devoted to postwar Catalan design of objects as diverse as urinals and human-sized inflatable pens. There is also a section on 20th-century ceramics, including many by Miró and Picasso.

Friday 21 to Monday 24, 10am-2pm.

This is the world's largest collection of funeral carriages and hearses, dating from the 18th century through to the 1950s. There are ornate Baroque carriages and more functional berlins and landaus, and a wonderful 1950s silver Buick. The white carriages were designed for children and virgins; there's a windowless black-velour mourning carriage for the forlorn mistress, ensuring both her presence and anonymity. The vehicles are manned by ghoulish dummies dressed in period gear whose eyes follow you around the room. Creepy good fun.

Saturday 22 & Sunday 23, 11am-6pm.

Can Framis was just another Poblenou factory at the end of the 18th century. In 2009 it was converted into a museum of contemporary painting, thanks to the Fundació Vila Casas. The pieces embrace different ideologies and creative languages. The walls of Can Framis hold some 300 works from artists born or resident in Catalonia from the 1960s to today – only the photography collection is within an international framework.

Monday 24, 10am-8pm.

The Museu Blau ('Blue Museum') started in 2011 in the Parc del Fòrum as part of the Natural Science Museum. All 9,000 square metres of it are spread over two floors. At the main entrance you're welcomed by the skeleton of a whale that beached itself on Catalan shores in 1862. The museum is made up of installations and spaces that include 'Planet Life,' an exhibition that takes you through the history of life and its co-evolution with Earth; the media library; and the Science Nest, where children up to age six can explore and play with natural materials.

Saturday 22, 10am-2pm, 3pm-8pm & Sunday 23 & Monday 24, 10am-3pm.

First off, you should rest easy knowing that 'bombers' is Catalan for 'firefighters'. This 'Firefighters Space' building was originally constructed for the 1929 International Exposition and was the first real fire station in Barcelona (until then the city had used other municipal buildings to house fire engines). Firefighters themselves helped design the structure, which was then used as a model for other stations throughout the city. When you enter, the first thing you’ll see is the Genoveva, a marvellously conserved and captivating fire truck from 1929. In the permanent exhibition hall, there are five spaces reserved for the display of items related to five different aspects of firefighting: the people, the equipment, the vehicles, the communicative instruments and the stations themselves.