The Minnesota Vikings learned an important lesson this week: Some people like to throw stones at glass houses, or in this case, glass stadiums.

A vandal in Minneapolis did some serious damage to the Vikings' new $1.1 billion stadium on Wednesday when they threw a rock through one of the windows at the building, which is known as U.S. Bank Stadium.

Already? U.S. Bank Stadium has a giant busted window. https://t.co/GIlSWpEFv8pic.twitter.com/oGMAUdkD6A — Star Tribune (@StarTribune) July 20, 2016

If you look at the picture above, you'll notice that part of the stadium design included putting rocks right next to the giant glass windows, something that the Vikings might want to reconsider going forward.

The outside of the new stadium is almost completely made of glass.

There's a lot of glass at the Vikings new stadium. Vikings.com

Although the damage doesn't look that serious, it's actually not going to be easy to fix. According to the Minneapolis Star-Tribune, the glass was custom designed for the stadium, which means it's going to take six-to-eight weeks for the design company to do repairs.

Despite the damage, the Vikings are still going to hold the ribbon-cutting ceremony that's scheduled to he held on Friday.

As for the damage itself, Minnesota Sports Facilities Authority (MSFA) spokeswoman Jenn Hathaway told the Star-Tribune that the MSFA planned for the occasional negative thing to happen to the stadium.

"Now that the building is open, accidents and vandalism occur," Hathaway said in a brief statement. "Addressing these issues is a normal part of building operations. Part of our operations protocol is to file a police report if there is vandalism to the building, which we have done."