Tate Modern, and the industrial building that makes it work

The signature spaceThe Turbine Hall, and why one artwork gets a whole room

The Turbine Hall measures roughly 3,400 square metres and runs the full 155-metre length of the building, five storeys of open volume that was, until the museum's 2016 Switch House extension, essentially unfillable by conventional means — which is exactly the point. Since 2000, an annual or biennial commission has handed the space to a single artist, and the results have become genuine cultural events: Olafur Eliasson's giant glowing sun, The Weather Project, in 2003, drew visitors who lay on the floor to look up at their own reflections in the mirrored ceiling; Ai Weiwei filled the floor with a hundred million individually hand-painted porcelain sunflower seeds in 2010; Doris Salcedo split the concrete floor itself with a 548-foot crack in 2007.

There is no separate ticket for the hall — it is visible and free the moment you walk in from the west entrance, and it is worth checking what the current commission is before you go, since the scale of the response varies from installation to installation and some years reward a longer visit than others. Whatever is showing, walk the full length of it at ground level and then look down on it from the bridge that crosses partway up on level 1 or from the balconies further up — the perspective changes completely.

The free viewSkip the paid observation decks — this one is free

The tenth-floor viewing level, at the top of the Blavatnik Building extension, gives a 360-degree panorama over London that costs nothing and requires no ticket — a genuine rarity in a city where The Shard charges upward of £25 for a comparable view. From here you get St Paul's Cathedral directly across the river framed by the Millennium Bridge, the City skyline behind it, and the length of the Thames in both directions.

The level was briefly at the centre of a privacy dispute after residents of the glass-walled Neo Bankside apartments next door objected to visitors being able to see directly into their flats, which led to screening being installed on one side of the terrace. It remains open and free, just with that one section obscured.

Go close to sunset if the weather cooperates — the light across the dome of St Paul's and the water below is the best version of this view, and it is far less crowded than the queue for a paid deck across the river would suggest.

Inside the galleriesHow the permanent collection is organised, and what to prioritise

Tate Modern breaks from the usual museum habit of hanging art in strict chronological order. Instead the collection across levels 2, 3 and 4 of both buildings is arranged into thematic groupings — around ideas like media networks, materials and objects, or artist and society — which means a Rothko might hang near a much more recent work exploring similar territory in colour or scale rather than sitting in a room of only 1950s abstraction. It rewards a slower, more associative way of looking than a conventional survey does.

The Rothko Room, level 3, holds several of the Seagram Murals — deep red and maroon canvases originally commissioned for a New York restaurant that Rothko later refused to deliver, donating them to Tate instead specifically because he wanted them seen away from a dining room. Elsewhere, the Surrealism and Objects rooms hold strong Dalí and Magritte, and the twentieth-century sculpture holdings include major Bourgeois pieces, including versions of her giant spider Maman that periodically stand outside the building itself.

Free admission covers all of this. Major loan exhibitions, held in the level 2 and 3 exhibition spaces, charge separate admission and are ticketed with timed entry — past blockbusters here have included major single-artist retrospectives that sell out their run, so book ahead if a specific show is the reason for your visit.

The building itselfWhat Herzog & de Meuron kept, and what they added

The renovation's defining choice was restraint: the architects left the brick shell, the industrial windows and the 99-metre chimney almost exactly as they found them, stripping the interior back to expose steel gantries and original fittings rather than smoothing everything into a neutral white-cube gallery. That decision is why the building still reads unmistakably as a power station even while functioning as one of the most-visited modern art museums in the world.

The 2016 addition, originally called the Switch House and now the Blavatnik Building, is a twisting ten-storey pyramid of perforated brick standing behind the original building, connected at several levels and adding both the tenth-floor viewpoint and a large amount of additional gallery space, including the Tanks — three subterranean oil tanks converted into some of the first purpose-built museum spaces anywhere for live art, performance and film.

The chimney itself, visible from across the river and much of south London, was originally intended by Scott to be shorter than St Paul's dome out of deference, and it still marks the building's roofline from a considerable distance — a useful landmark if you are walking along the South Bank and trying to judge how far you still have to go.

Making the visit workTiming it, and pairing it with the rest of the South Bank

Tate Modern does not require advance booking for the permanent collection, and it is one of the least crowded major London museums relative to its size, particularly on weekday mornings. Weekend afternoons draw the heaviest footfall, largely concentrated in the Turbine Hall and around whatever the current headline exhibition is.

The building sits directly on the Thames Path, connected to St Paul's on the north bank by the Millennium Bridge — the pedestrian bridge that famously had to be closed for retrofitting within days of its 2000 opening after it swayed alarmingly underfoot, now a stable and genuinely pleasant five-minute crossing with one of the best photo angles of the dome in the city.

Borough Market sits a ten-minute walk east along the river, making a natural pairing for a late morning at the gallery followed by lunch among the market stalls, and Shakespeare's Globe, a reconstruction of the Elizabethan playhouse, is immediately next door if you want to extend the afternoon further along Bankside.