There are few things construction nerds look forward to more than caisson work. It marks the unofficial “official start” of skyscraper construction, people are digging in the dirt, heavy machinery dances around each other, and loud noises bounce off neighboring buildings. You might not think it’d be fun to watch, but it’s mesmerizing. Which is why some of us stand there and take dozens of photos.

Last week marked the beginning of caisson work at 354 North Union. Big shout-outs to Stalworth Underground and Onni Group for providing the entertainment. Here are dozens of photos:

CTA and Metra rides, Zipcars, Divvy bikes, camera lenses, and solid walking shoes add up. You can help offset expenses with a greatly-appreciated donation to Building Up Chicago.