Every Sunday this summer, we'll be taking an historical tour of the Hollywood blockbuster by examining an older film that is in some way a spiritual precursor to one of the weekend's wide releases. This week: the grueling Transformers: Dark of the Moon is not original in any meaningful way, and does not claim to be. Among the many, many tropes given a workout is the humanoid robot, which can come, as it does there, in the form of building-sized alien machines that transform into cars; or it can come in the form of a human -sized machine pretending to be a sexy Weimar lady.

If a movie can be reasonably classified as "science fiction", and it was made in the last eight and a half decades, it was influenced by the 1927 Germany film Metropolis. Simple as that. It was not the first of its kind - define the phrase loosely enough, and there are sci-fi films dating back to the 19th Century - but its effect on the iconography and narrative structure of its genre has been incalculable. I don't know of another film at any point in history that casts such a long shadow over so many descendants; perhaps the 1931 M and the crime thriller, meaning that Fritz Lang directed arguably the two most influential motion pictures of all time, and is therefore the most important director in film history.

Perhaps because of its cartoonishly huge legacy Metropolis is a perfect gateway drug for old movies. It is among that certain breed of film that is regarded as a classic and artsy for the single reason that it is old; but it is, taken objectively, pretty much like any modern Big Dumb Popcorn Movie, albeit made by a significant visual genius - but when one learns that it was a hugely expensive proposition, it nearly bankrupted the legendary UFA studio, and it required the invention of brand new ways of doing visual effects, doesn't it start to sound a little bit less like the contemporaneous Sunrise and a little bit more like Avatar? Which probably has at least a few people recoiling in a fit of nausea, but consider: a film chiefly discussed for the glories of its production design, which represented the absolutely pinnacle of visual creativity at the time it was made, while the plot itself involves characters who are only barely expressed, one of whom is a ridiculously unsubtle Messiah figure who throws himself in with the fate of the "other" society that his people are exploiting, all tied up in a theme about how we need peace and love to get along, which is itself put forward with the wit and cunning of a pie to the face. Also, explosions.

It is of course indisputable that Metropolis, being as it is one of the last grand gestures of German Expressionism in its pure form, is an accomplished piece of filmmaking on a level that no contemporary blockbuster auteur is even daydreaming about, but the fact remains: this is, at its heart, a movie about spectacle over substance, pure sensory overload counteracting a boilerplate message that could have come out of a dime novel. The phrase "The mediator between the head and the hands must be the heart!" is trotted out a simply indecent number of times throughout the film, because dammit, Metropolis ain't interested in the small. It is a big huge motherfucker of a picture.

Maybe for this exact reason, it remains one of the most popular of all silent films; I am not going to be so brash as to argue that it is the most popular silent film among modern viewers, but if I was going to, I'd begin by pointing out that it's the highest-rated silent on the IMDb Top 250 (a barbaric and inapt measuring stick, but it at least gets us on the road to what the normals like to see in their movies). It does all the work for you; all you have to do is sit and be amazed.

The good news, then, is that Metropolis isn't just amazing it is A-Maze-Ing: maybe, frame-for-frame, the most jaw-dropping science fiction extravaganza ever filmed. Is it not true that a mere two decades on, we look to Jurassic Park with the coziness of nostalgia? and are not the Lord of the Rings movies already covered with a layer of easy familiarity? and isn't it so that even Avatar itself already looks a bit "done", and we can all nod our heads sagely and intone, "it does look beautiful, but that script!" But Metropolis, well past its 80th birthday, is a film that I can never re-watch without being absolutely laid flat by the oh-my-God-they-made-this?-ness of its humongously ambitious mise en scène. Every time it's like one is seeing it new; though our current filmmakers' toys are undoubtedly more complex than this, no one has yet figured out how to be more inventive.

Now, I have gone on and on about how much Metropolis is all about the visual wow and not about the script, but I am being needlessly monochromatic in doing so. Truth is, the story and the visuals in this film are inseparable: it is through the image that the story's fullest dimensions are explored, while the imagery only attains the gravity that makes it more than a cheap gimmick because of the considerable sincerity of Thea von Harbou's script. The movie takes place in Metropolis, an unimaginable vast city of the future lead by Joh Fredersen (Alfred Abel). The city is powered by the grueling labor of a huge underclass whose lives consist of nothing but work and sleep, moving from their terrible labor to the sunless vaults where their housing is located. Above them, in the massive skyscrapers that make up the whole city, the wealthy live in fabulous luxury, none more fabulously than Freder (Gustav FrΓΆhlich), the son of Joh Fredersen.

It happens one day that Maria (Brigitte Helm), an inspirational thinker who has been teaching the laboring class that they deserve basic human respect, finds her way into the ostentatious gardens where Freder chases high-class whores. Freder is instantly struck by this beautiful woman, and her arguments, and devotes himself on the spot to learning more about the workers who enable his outstandingly idle life: he sneaks into the underground, trades places with a worker named Georgy (Erwin Biswanger), and finds out in no time at all that this is not a life, but a constant torment.

In the meantime, his father has met with the wicked scientist Rotwang (Rudolf Klein-Rogge), who has just completed a mechanical man, that can be made to look like anyone. Seeing an opportunity to crush this worker movement, Fredersen instructs Rotwang to fashion the robot after Maria, but the inventor has other plans: destroying Metropolis itself, his way of exacting revenge for the woman that, many years ago, Fredersen stole away from him.

Big melodrama on the one hand - a relentlessly earnest message about social justice that took dead aim at the licentious excess of Weimar Germany on the other - Metropolis's blend of the sensational and the serious would be echoed in countless movies down the line, but the thing it has that they don't have is Fritz Lang. A director of a singularly geometric bent throughout his careers, Lang's compositions in Metropolis are particularly linear: focused on the vertical lines of the buildings, the horizontal lines of workers dragging themselves through machines, jagged diagonal lines (one of the film's most beautiful shots depicts the workers as the spokes in a giant wheel; another presents the great steam engine at the center of the city as a massive collection of squares, in each square a single human being moving as rigidly as the gears they manipulate - Lang immediately literalises this image as a huge beast eating the bodies of the workers, but it's a largely unnecessary flourish).

I'm going to cut myself off: the film is obsessed with imagery reducing humans to functional elements of a machine - even the wealthy privileged folks. In one of the film's most iconic scenes, the robot Maria dances "erotically", her gyrations moving along strict, unyielding angles and planes; that this arouses the lust of the upper-class men who watch her is plain, but it's hard to imagine any viewer not finding it silly or vaguely disgusting. It is undeniably the dance of a robot, all in all, and that such roboticism is seen as sexual within the world of the film is a particularly cutting example of how the human has been replaced by the mechanical in this broken, if shiny, future.

No accident at all, in fact, the most of the most famous moments in the film center on Maria the robot: not only because Helm gives the only performance in the movie that is particularly good, or particularly anything, but because this first robot in feature-length cinema speaks so powerfully to the dehumanisation of society that makes up the meat and potatoes of Metropolis. It is less an abomination than a natural extension of an increasingly mechanical world, one that cheapens landowner and worker alike. That this somewhat belabored theme never slows Metropolis down is testament to just how wonderfully cool it all looks - and really, words can never match the experience of just watching the thing - cool even by today's standards, though it looks a hell of a lot more like Berlin in the '20s that anything we're apt to see in the future (and undoubtedly, this was not an accident). Would that more of the shiny space epics to follow in its wake had possessed a quarter of Lang's visionary sensibility.

NB: The whole affair of how many damn different versions of the film exists is fascinating, but it need not concern us here: the short version is that in this case, longer is clearly better (in all but the most complete cut, missing only a few minutes divided between two scenes, two characters are essentially removed), so be sure to check out the cut restored in 2009 and released in 2010; parts of it look like hell, but the film has never been so crisp and clear in its storytelling, and some iconic moments turn out to have a very different impact than you thought - Freder's goggle-eyed stare during robot Maria's dance in particular takes on an extraordinary new meaning.