NATICK – It wasn’t a good sale or a few irresistible deals that stopped Natick Mall shoppers in their tracks Saturday afternoon.

It was a 25-foot-long replica of the U.S. Capitol building made of Legos instead.

“I’m trying to visualize people in a room putting it together,” said Shirley Stahl, of Ashland.

Snapping photos and videos, groups stood around the model, one of 10 on display throughout the mall until Sept. 24, in awe.

It’s not the run-of-the-mill Lego set and certainly not one that can be found boxed up on the shelves of a toy store.

It’s part of the Lego Americana Roadshow – a mobile tour that brings the miniature building as well as other Lego-made national landmarks such the White House and the Washington Monument around the country.

The show, which first kicked off in Natick three years ago, has crisscrossed the country for the last three years, hitting nine locations each year, according to Andrew Little, Lego American Roadshow tour manager.

Creating the structures takes a lot of Lego bricks – and time, too.

A model of the White House took 825 hours to complete and the U.S. Supreme Court building took 450 hours. The Lego-studded Washington Monument towers more than 15 feet tall.

For those wondering who might have that kind of time on their hands, the answer is Lego’s “master builders,” according to Little.

This group of Lego experts created each model in the company’s Connecticut headquarters by hand.

And despite his experience on the tour, Little said he still shares the same amazement that washed over the faces of mall goers Saturday.

“This is the 27th time I’ve set it up and I’m always amazed every single time,” he said.

Maxwell Delinsky, 7, of Wellesley, visiting the mall to check out the latest Lego sets, said the largest model he ever built was about 5,000 pieces.

The size of those on display is what impressed him most, he said.

Taking her best guess, Kristin Stahl, of Ashland, estimated the U.S. Capitol model was made up of about half a million bricks.

“I went with 500,000, but I think it is more than that,” she said. Sorry, the definitive number will not be provided here as the guessing game is part of a contest.

A few passersby said the exhibit conjured up memories of their childhoods spent clicking the small plastic pieces together into creation all their own.

Others, such as Faramarz Dowlatshahi, of Framingham, shook their heads.

“It’s amazing,” he said, as he studied over the finer details of the U.S. Supreme Court model. “Absolutely amazing.”

Christopher Gavin can be reached at 508 634-7582 or cgavin@wickedlocal.com. Follow him on Twitter @c_gavinMDN