“Metropolis” is even trickier, having so many cuts of varying lengths, not to mention soundtracks silent or provided.

Recently, as you may have heard and read, lost footage from Lang’s 1927 masterpiece was discovered, finally making “Metropolis” complete, as Lang intended, for the first time since its roundly dismissed theatrical debut in its native Germany. In the U.S., Kino International released it around the holidays as “The Complete Metropolis,” but I’m inclined to say cinephiles with region-free players may want to opt instead for the UK release by Eureka!, under its “Masters of Cinema” series.

From box to booklet, its packaging is superior, making it feel more like the definitive historical document it should be. I can’t tell a difference in picture or sound between one or the other, but Eureka!’s does contain full-length commentary, in which film scholars Jonathan Rosenbaum and David Kalat (whose “J-Horror” book I’m currently in the middle of reading, incidentally) discuss how each viewing of this “work of pure cinema” changes with each viewing: “The longer each version has gotten, the more interesting the film has gotten.”

That’s true. Whether it’s your first time or my fifth, watching “Metropolis” is nothing short of a visual revelation. Admittedly, its story isn’t the easiest to follow, but its futuristic cityscapes and structure designs never fail to astound. It is simply a beautiful look just to look at, and would be even without the aid of title cards as a narrative stand-in. Even today, I cannot figure out how some of the effects — like the electric rings bobbing up and down around the robot’s body — were achieved. To say the film was ahead of its time remains a massive understatement.

A new, near-hourlong documentary is a must, but be prepared to read subtitles, as it contains no English-language option. Among many things, the piece reveals that Lang first hated his film; takes viewers on an architectural tour of futuristic edifices that inspired him; discusses the iconic robot, Maria; compares the American and German edits side by side, shot with two different cameras; and addresses the restoration process, where stills were considered to sub for lost scenes before the footage turned up.

It’s also nice to see music producer Giorgio Moroder’s controversial 1984 edit included in the doc’s scope of coverage. His cutting it to the bone and adding a hot (at the time) rock soundtrack may have made it accessible to younger generations, but it would be nice to have had this alternate version included, however now-dated. And if that’s the only negative thing one has to say, that qualifies as a must-own. —Rod Lott

Read how Alley Orchestra gives “Metropolis” a new, fresh sound at live screenings.