If you aren't already counting the days until "The Avengers: Age of Ultron" hits theaters (spoiler hint: it's more than 400 but less than 1,000,000), then perhaps today is a good day to start.

Writer-director Joss Whedon's "Avengers" sequel has officially entered production, with two weeks of filming in Johannesburg, South Africa, beginning Tuesday (February 11).

The two-week shoot is expected to cause major traffic disruptions, with numerous road closures being reported by Independent Online -- with certain roads being closed for 24 hours a day.

"We're thrilled that Marvel Studios is bringing a major motion picture project to Joburg," said Gauteng Film Commission chief executive Phindile Mbanjwa of the "Avengers" sequel's two-week stint in South Africa. Frankly, we're thrilled, too -- because it means that the long-awaited sequel to the most successful comic book movie of all time, commercially and otherwise, is one step closer to reality.

Of course, even as production begins, there are so many questions surrounding "Age of Ultron." Despite the robust cast it already features, there's talk of additional roles that still need to be filled, including Carol Danvers, best known to Marvel Comics readers as Captain Marvel; it's been rumored that she has a part to play in the "Avengers" sequel.

There was also some hope that T'Challa, the Black Panther of Wakanda, might make an appearance in "Age of Ultron," fueled in large by the sequel's South Africa production. But the Gauteng Film Commission revealed Monday that the "Avengers" team is "shooting Johannesburg as Johannesburg," seemingly ending speculation that Wakanda is in play. (The report further revealed that the Johannesburg-set sequence plays into the film's first 10 minutes.)

Still, there's much about "Age of Ultron" that we do know. We know that veteran heroes Iron Man, Captain America, Thor, Hulk, Black Widow and Hawkeye are all back for more. We know that there's a new villain in [article id="1720507"]Baron Von Strucker, played by Thomas Kretschmann[/article]. We know that we'll meet "the twins," [article id="1716594"]Quicksilver[/article] and [article id="1712714"]Scarlet Witch[/article], played by Aaron Taylor-Johnson and Elizabeth Olsen, even if we're not quite sure whose side they're on.

We know that [article id="1713302"]James Spader will play the titular Ultron[/article], and we know that another android is in play as well: [article id="1721941"]Paul Bettany as Vision[/article], marking a major upgrade for the actor who has voiced Tony Stark's J.A.R.V.I.S. system over the course of four Marvel Studios pictures.

Most important of all, we know this: "Age of Ultron" is yet another ambitious project from the house that Iron Man built, with Whedon and Marvel head honcho Kevin Feige behind the wheel. It's a powerhouse team that's brought in billions of dollars and countless fans across the world. To say there's reason to get excited for the "Avengers" sequel -- even just as it's starting production, even when it's more than a year away -- is Earth's mightiest understatement.

"The Avengers: Age of Ultron" hits theaters on May 1, 2015.