Ever since I first played the original Marvel vs. Capcom back in 1998, I've always been fascinated by this background (images from the Fight-A-Base and Slateman sites):
The setting looks like the ultimate sci-fi terrorist organization's lair complete with a mysterious boss, flashing holograms of major agents, scientists, and countless minions. MVC's other backgrounds are clear references to particular Marvel and Capcom lore: E.Honda's bathhouse from Street Fighter, a Zabel Zarock concert from Vampire, St. Petersburg from Strider Hiryu, Dr. Wily's lab from Rockman, a command center from Avengers, the Daily Bugle from Spider-Man, the blue area of the moon from Fantastic Four.
But from what I've been able to determine, this particular background is far removed from the origins of its inspiration. The only conceivable reference available is to Capcom's Lost Worlds (much more well known in the US as Forgotten Worlds). The 2 giants depicted, Raijin and Fujin, are bosses from this game (and clearly inspired by Hokuto no Ken's Raiga and Fuga). The shadowy villain is almost certainly Bios, the primary antagonist in Lost Worlds.
However, nobody seems to know where all the other unique characters in the background are from. There has been speculation that the hologram characters represent the bosses from Lost Worlds but the numbers don't exactly add up—7 bosses to 9 characters. However, if we assume that Raijin and Fujin are supposed to be mecha each piloted by a character, then the numbers would actually fit. Given that one of the hologram pictures looks like Cleopatra, she would explain one of the mysterious quotes from the game: "Darn it! My date with Cleopatra is spoiled!" And one of the hologram pictures looks like a pharaoh, which would be match for the Tut boss from Lost Worlds (
http://www.arcadequartermaster.com/capcom/fw_bosses.html).
But then who are the 5 characters atop the pillars? They certainly aren't the 2 playable Unknown Soldiers. And they don't appear to look the same as any of the hologram characters. Nobody has a credible idea. Ultimately, this background is still full of mysteries. Is there a Japan-only novel or manga that fleshes out Lost Worlds's setting and explains some of these elements? If so, even their MVC fans don't seem to have the answers. Or was this background a new idea by MVC designers to reinterpret the Lost Worlds universe? If so, nobody seems to have their concept notes. If anybody here knows, please do tell.