Building a road might be harder than you'd think, but we all know that building a bridge is one serious feat of engineering. Here's some proof: 42,000 hours of work time-lapsed down to a hypnotizing 4-minute sprint.

EarthCam has been pointing its robot eyes turned San Francisco-Oakland Bay Bridge-ward since 2008, and in that time it's collected some 2 million images of the $6.4 billion project. Put together in sequence, they're stunning.

The newly finished span of bridge is due to open by 5 AM Tuesday at the latest, nearly 25 whole years after the 6.9-magnitude Loma Prieta quake took out a chunk of it back in 1989. The modified bridge is designed to handle the strongest possible quake that's likely to hit the area within the next 1,500 years.

It's been a long, hard, delay-riddled road to completion, one that took a lot longer than 4 minutes to travel. But wow is it ever incredible to see it coming together before your very eyes. [EarthCam, ABC News]