From the 17th-storey roof terrace of whats commonly called the Paddington Cube, Londons cityscape unspools with leisurely aplomb. To the south, the trees are turning brown in Hyde Park; to the north, the still terraforming Paddington Basin features a jostling cluster of disparate buildings, like over-dressed guests at a cocktail party studiously trying to ignore each other. To the east, the Citys multifarious extrusions of capitalism dominate the horizon presided over by the hypodermic pinnacle of the Shard. Yet, if the Shards developer, Irvine Sellar, had realised his original ambition for Paddington, the Shard would have had a twin: a 72-storey, 254m-high tower that quickly became known as the Paddington Pole, the pair winking conspiratorially at each other across central London.The ensuing saga of how the Pole became the Cube was measured out in the minutiae of planning and legal battles but, from the getgo, there was a torrent of spitting feathers outrage from heritage groups and the local community over its Brobdingnagian scale. An online petition opposing it attracted 1,800 signatures. Where the Shard exuded a swashbuckling swagger in a part of London already in thrall to tall buildings, the Pole seemed like an opportunistic pale imitation, audaciously out of sync with its surroundings, dwarfing Paddington Station and the neighbouring St Marys Hospital and looming over the localitys agreeable Victorian terraces and squares.AdvertisementUltimately, the outrage proved insuperable and Westminster planners rebuffed the scheme. So, just like that, Sellar and his architect, Renzo Piano, went back to the drawing board and lopped off 65 storeys, a volte-face that was a gift to architectural magazine headline writers. Pole-axed, trumpeted Building magazine. The scheme also changed from being residential-led (the views from those literally high-end apartments doubtless commanding huge premiums) to being essentially a shell-and-core office block.Sellar, a man who once said with the Shard, we can kick sand in the face of the Eiffel Tower and whose urge to reshape the London skyline seemingly knew no bounds, was phlegmatic about this reverse ferret, as was Piano. I was a bit surprised by the criticism; but theres a lack of love for towers in England, where theyve long been seen as symbols of power and arrogance, he told the AJ in 2016.Paradoxically, after all the hoo-hah, the Cube does everything it can to blend in. It appears made of a singular material glass and is of a singular colour, a kind of pale, milky grey, as if it had been batch-dipped; practically the same hue as the roof of Paddington Station. Homogenous, crystalline and curiously self-effacing, despite its cubic chonk, its sheer flanks of low-iron glass reflect the mutable London sky. Derived in part from studies of the lace-like station vaults, full-height glazing modules a mere 1.5m wide, held in place by slim structural fins, ripple around its colossal, four-square volume.Apart from its notched corners, where the structure is exposed and expressed with some discreet cross-bracing, the Cube has a glacial, Euclidian perfection. Theres also a scenic exterior lift set within a skeletal tower clamped to its west side, another residual hint of Pianos High-Tech proclivities, that will whizz diners up from the pavement to a penthouse eatery (West Londons highest rooftop restaurant). But this polite and refined ghost building is, perhaps predictably, a very far cry from the batshit exuberance of the Pompidou Centre.The schemes genesis lay in the changing post-industrial patterns of use around Paddington Station, specifically the historic link between rail and mail. The Cube occupies the site of the former Paddington Sorting and Post Office, originally designed by Henry Tanner in 1892, and later extended in 1907 by Jasper Wager. Strategically situated next to the station, it leveraged this infrastructural proximity to convey mail on trains across the west of England. But, as mail volumes declined, it was vacated in 2010 and remained unlisted and unloved. Its subsequent removal paved the way for a major and much-needed redevelopment of the area around Paddington Station. For Sellar and Piano, there were clear parallels with London Bridge and the Shard, in how a station-adjacent showpiece building could intensify and reactivate a languishing part of the city.AdvertisementEmblematic of Victorian engineering puissance, Paddington has assumed a kind of national treasure status. When completed in 1854, Brunels iron and glass tour-de-force could claim to be the largest train shed roof in the world. Yet, for decades, the user experience was unspeakably dismal, with no sense of arrival and no obvious station front door, exacerbated by a chaotic and inhospitable public realm. Passengers were siphoned down a busy vehicle ramp from Praed Street to an underwhelming entrance resembling a giant mousehole, where the stations undulating roofscape telescopes down to a single bay.Where the Cube is rational and repetitive above ground, with its slickly stacked floor plates, where it meets the ground it becomes more subverted and fractured, catalysing and shaping a new public realm. This is how most people will encounter it and its fair to say that the experiential uplift is palpable. The dismal ramp is now a paved piazza, with steps around its edge and new landscaping, part of a network of spaces and routes designed to embed the station more legibly and logically into its wider surroundings.A key move is the creation of a diagonal axis across the footprint of the Cube, which forms a subterranean concourse connecting with a new entrance to the Bakerloo line. This also opens up views through to the main station, so people can see where they going. A familiar gamut of shops and cafs activates the ground plane and specially commissioned artworks, including a serpentine sculpture by American multimedia artist Pae White precipitously suspended over the Bakerloo concourse, add further visual incident. The area is sheltered by a large glass canopy suspended from the base of the Cube. Flaring out like a protective tutu, this also marks the distinction between public and corporate realms. To access the Cube, you ascend an external bank of escalators to the entrance, where a softly lit and softly furnished concourse straight from the playbook of WeWork is contrived to winkle people out of offices for a spot of informal interaction. Lower floors have fugitive, Rear Window-style views of neighbouring buildings, from the hospital campus of St Marys to assorted hotels, while upper levels enjoy master of the universe panoramas.Irvine Sellar died in 2017, as the Cube was making its not uneventful way through the planning system, so he never saw it completed. Yet, though Sellar was denied a second trophy tower, the outcome is still, in its way, a showpiece, albeit more demure in form and scale, the yin to the Shards yang. But beyond the fixed point of the building and its architecture, how it reimagines the public realm and redefines what goes on around it, transforming the day-to-day experience of station users and the wider Paddington populace, is ultimately just as if not more consequential. Perhaps its not always the size of the ship but the size of the waves.Catherine Slessor is a writer and critic and president of The Twentieth Century SocietyProject dataStart on site November 2019Completion December 2022 (offices), September 2024 (public realm)Gross internal floor area 63,000mConstruction cost UndisclosedArchitect Renzo Piano Building WorkshopClient Great Western Development with Sellar Property GroupExecutive architect Adamson Associates ArchitectsInterior designer Universal Design StudioStructural engineer WSP StructuresM&E consultant WSPCost consultant Gardiner & TheobaldProject manager Gardiner & TheobaldPrincipal designer Adamson Associates (International)Approved building inspector Sweco Building ControlAccess consultant David Bonnett AssociatesLighting designer Cosil-Peutz Lighting DesignLandscape designer BDP, Flora FormMain contractor MaceCAD software used RevitAnnual CO2 emissions 149kgCO2/m2