What a week to be a fan of Silent Era cinema! On Tuesday, four classics were released on both DVD and Blu-ray, presenting work by three of the best-known artists to emerge during that period.

Physical comedy pioneer Buster Keaton played detective and time traveler in "Steamboat Bill, Jr." and "Three Ages," respectively, which are bundled in a double-feature disc from Kino. These aren't the first Keaton romps Kino has offered on Blu-ray, and I trust they won't be the last.

Meanwhile, the cinemaniacs at Criterion have found more bonus material for Charlie Chaplin's sound-era "Modern Times" than you'd think could exist. Old home movies and outtakes are joined by newly produced extras such as a featurette on its visual and sound effects. In between those is a short 1967 documentary about Cuban moviegoers encountering the movie for the first time. Here's hoping Criterion makes a habit of Chaplin reissues the way Kino has of Keaton ones.

But the newsiest item is a disc devoted to Fritz Lang's seminal sci-fi epic "Metropolis." "Metropolis" is one of those movies that has undergone many restorations over the years: Lang's studio trimmed his preferred edit down when it first released it, and the tale was brutally altered when it first got American distribution.

All intact prints of the original cut are thought to have vanished, but every few years a new source seems to pop up, letting historians play Dr. Frankenstein and graft newly uncovered material back onto the old. Most recently, about 25 minutes of unseen footage was discovered in the vaults of a Buenos Aires museum where other hitherto vanished silent films have been found.

The Buenos Aires relic was in poor condition, which means the newly patched-together "Complete Metropolis" (as Kino has, somewhat dubiously, named it) doesn't look as pristine as one might wish. But the visual flaws are actually kind of helpful, as they allow a scene-by-scene awareness of what fans are seeing now for the first time: While most of this new version looks great, the image becomes grainy and discolored where new scenes have been added, showing us exactly what studio editors excised.

While some of those cutting-room-floor shots are trivial, others are far from it. Distributors intended to simplify the story by cutting it down, but only now do some of the tale's melodramatic conflicts really make sense. The movie is no longer simply a storehouse of iconic dystopian sci-fi imagery (the inspiration for "Blade Runner" and so many others), but a mythlike saga of class conflict and conscience-awakening whose characters actually, for the first time, have reasons to do the things they do.

Now if only those Buenos Aires archivists could stumble across some of those elusive Orson Welles projects...