Will Smith Walks Through Deserted Zurich, Compares It to 'I Am Legend'

Will Smith might want to start gearing up for the apocalypse ... 'cause he seemed to have the streets all to himself in the early morning -- and, it got him thinking about "I Am Legend."

The actor shared a video to Instagram ... telling fans he's walking through Zurich, Switzerland, in the early hours and flashing back to the hit 2007 flick -- 'cause he says he's not seeing another soul.

Smith explains he's only in Zurich because his plane couldn't take off ... unclear why exactly he's in Europe -- but, he says he needed to spend the night.

WS says it's so quiet ... with the loudest noise coming from a particularly vocal crow he tries to shush into submission.

But, one moment does get Will's voice raised due to excitement ... 'cause he geeks out when he sees a particularly well-known Swiss item -- watch the clip until the end to see the star fangirl.

Will's going to need to dive back into the "I Am Legend" mindset soon enough ... 'cause the sequel's coming soon -- and will feature Hollywood hunk Michael B. Jordan.

During a recent interview with People, Michael confirmed he's working on the script with Will ... adding the movie's coming along nicely.

Fans of the film will know Will's character (MAJOR SPOILER HERE) dies in the original theatrical version ... but, an alternate ending on the DVD sees him escape with his life -- and, that's the ending filmmakers are running with.