Cementing a reputationOne of London’s finest landmarks belongs to one of London’s least-used railway lines.

It represents the highest point on the Underground network above ground (almost 18 metres in height) but serves a station that is visited by close to the fewest number of passengers on the whole of the network to which it belongs.

It’s an object of awe-inducing size and unquestionable beauty, yet chances are it is rarely seen by anyone in the capital save those who live and work in the neighbourhood.

Out in any weatherThe viaduct that carries that Northern line from Finchley Central over the Dollis Brook to Mill Hill East is impossible to appreciate while inside a carriage trundling across its top.

You can pick up a sense of the structure’s accomplishments by virtue of the views across the surrounding countryside (and it is countryside, even here, in the centre of the borough of Barnet). But you need to make a five-minute journey on foot from either station to the valley floor to sample its full wonder.

The archesTo stand underneath one of its arches is a rather giddy experience. Everything is simply so… big. So fantastically, addictively, uncompromisingly big. But not big in a bombastic, ill-conceived way. This is big done with foresight, skill and style.

Thousands upon thousands of bricks curve, glide and dance in every direction. The sun throws shadows that are both scintillating and eerie, and which play out against huge bursts of illumination:

More archesThe viaduct has been in use since 1867. John Fowler is the man to thank, the genius (and for once the word is justified) who acted as chief engineer for the very first chunk of the Underground, the Metropolitan railway; the Forth railway bridge; Grosvenor Bridge, the first railway bridge over the Thames; the original stations at Liverpool Central, Manchester Central, Sheffield Victoria and St Enoch in Glasgow; and many other highlights of Victorian civil engineering.

It’s almost laughable that the paltry single stump of a track that runs apologetically from Finchley Central to Mill Hill East has been blessed with such splendour and majesty.

But that’s what makes the Underground so great: that its artistic peaks often lie among its remunerative troughs, yet both somehow continue to exist, side-by-side.

I dream my dreams away

*Con*crete? No! PRO-crete!An especially ghastly phrase to have entered the modern business lexicon – one of many – is “do a deep dive”. “Let’s do a deep dive into these figures,” people say, and expect you to be impressed. Instead you are rankled, because the phrase is meaningless and exists solely to make its speaker feel like they sound professional.

You cannot dive, deep or otherwise, into figures. What you can do is dive into something that exists, and which is tangible. The exceptional Bermondsey station allows you to dive deeply – not literally, mind – into a catacomb of concrete that, thanks to its breathtaking design by Ian Ritchie, never once loses sight of daylight.

Beginning to see the lightInformation about the project’s history on Ritchie’s website, particularly the concept drawings, make clear what was intended from the outset: to bring “a perceptible sensitivity and ambience to the public” by using “natural light and a clear spatial experience”.

He and his team succeeded completely. The impression of enormous, liberating space is fuelled by the sympathetic illumination – and vice versa:

The future is here - and it's concrete!It’s great to be reminded of how awe-inspiring concrete can look when deployed in ways not common to the ordinary high street or suburban road.

And Ritchie seems to want us to dive both physically into the ground but figuratively into our imaginations, to touch on deep associations we have with what might pass for a futuristic world:

Deeper and downBermondsey is another gem of a station on the Jubilee line extension. I’d honestly not expected, so early into this 150, for the Jubilee to be the line way out in front in terms of mentions. But there you go. So much for Charles Holden (for now, at least).

Suburbanisation of the DaleksFrom the tip of the roof downwards, Southgate is something very special.

It holds its own against fierce competition from pretty much every station along the northern end of the Piccadilly line, which is easily the most rewarding stamping ground for Underground architecture. And it does this by not merely being another example of Charles Holden’s faultless skill for coupling beauty with design, but by being unique.

There is literally no other station like this on the whole of the network.

The Underground has landedThere’s a sense here that Holden set out to push as far as he dared the expectations for and acceptance of how an Underground station should appear in a suburban high street.

You might think he failed, or that he went too far. I think he succeeds with aplomb.

Agreed, it does look like Southgate station has landed from some other time and place, even some other world. But it doesn’t feel out of time or out of place. Maybe that’s because we’ve all got so used to seeing this kind of extraordinary architecture in ordinary surroundings. But perhaps that’s all the more reason to continue to draw attention to it – and to appreciate and marvel at it even more, Dalek stalk and all:

Another 'Holden Globe award' winnerIt opened in 1933 and is now Grade II* listed. There’s no steel or iron here: just brick, concrete and glass, singing in perfect harmony.

The interior, which I’ll cover another time, and which explains how that dazzling circular roof appears to be entirely self-supporting, was renovated in 2008. The majestic exterior is pretty much unchanged.

It’s not something you can easily take in just by standing still. If you’re like me – which you’re probably glad you’re not – you’ll end up walking all the way round the outside. Twice.

Oh, and as if we weren’t spoiled enough, Holden throws this in to boot:

Look! Over here!It’s a massive roundel adjacent to the station entrance, that in turn supports an enormous illuminated turret – just in case you hadn’t noticed the Underground calls here.

Now if only Transport for London licensed desk lamps that looked like this…