SPOKANE, Wash. -

An art project has taken shape on the north side of the Monroe Street bridge, where someone is using fractured basalt to create several galleries of rock sculptures.

They are called cairns and throughout history have been used to mark hard to spot trails or hazards ahead. In this case they are more of an ad hoc expression of art but no one seems to know who the heavy lifting artist – or artists -- is.

Kendall Yards is already home to a growing collection of outdoor art.

“We have some permanent art installations as well as some installations coming up in the future and we invite everyone to come down and enjoy the wonderful art we have on site,” Cat Carrel with Greenstone Homes said.

Recently some unexpected art has showed up here as well, the cairns, carefully stacked towers of rock.

“Well the cairns are kind of an interesting phenomenon, they just kind of popped up and we're not sure who did them, or how long they'll stay but for now I think they're pretty cool,” Carrel said.

Someone has put a lot of time into this hard rock project; they've been using counterweights and gravity to make these sculptures larger and more durable, with some of weighing more than 200 pounds.

The artists have even incorporated pieces of construction debris to give their creations a little more flair.

“I like that it's anonymous and I like that someone is creating beauty for everyone to see,” student Taylor Jamison said.

Kendall Yards Developer Jim Frank, who's an art fan himself, says the cairns can stay for now.

“As far as I know the cairns are going to stay until something else happens on that lot,” Carrel said.