Perhaps laying a bed of rocks next to a big glass house wasn't the best idea.

On Wednesday morning, stadium officials — and pedestrians, as well as passersby in cars, trains and buses — could see a broken window at ground level of the newly completed, not-yet-open U.S. Bank Stadium.

And it's going to remain broken for a while.

It's likely to take six to eight weeks to receive and install a new pane because the glass is custom to the building, according to a source with knowledge of the situation.

The break leaves the building in less-than-perfect condition for the ribbon-cutting Friday in which hundreds will fill the field to watch dignitaries congratulate each other about the $1.1 billion building that was the largest public-private effort in state history. According to the source, the glass was broken by someone walking along the north side of the building who picked up a rock and threw it at the ground-level wall of glass.

"They got it on the security camera," the person said.

An exterior pane, about 10 feet by 5 feet, shattered, leaving a hole big enough for a small human to crawl through.

A second interior pane prevents an opening in the facade.

The pedestrian-vandal was using the sidewalk that is bordered by the club's windows on one side and piles of decorative rock on the other.

Whether the passerby grabbed a rock from that pile couldn't be confirmed by Minnesota Sports Facilities Authority (MSFA) spokeswoman Jenn Hathaway.

The broken glass is part of the Hyundai Club area, a space MSFA Chairwoman Michele Kelm-Helgen touted on Tuesday during a media tour as a favorite for corporate rentals and gatherings.

The window was intact during the tour.

Kelm-Helgen also talked about a unique feature of the Hyundai Club that gives direct access into the club from a dedicated doorway along the wall of windows instead of one of the building's main gates.

The windows in the club face northward, toward the Minneapolis Mill District.

The broken pane can be seen by riders on light-rail transit cars passing by the northern face of the building.

"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."

She said the MSFA is reviewing whether the video surveillance footage can be made public.

More than 100,000 visitors have tickets to the free open house and celebration at the building beginning Saturday.

Tickets are still available through Ticketmaster.

Rochelle Olson • 612-673-1747