PORTLAND, Ore. — Portland City Hall has taken a beating over the years.

Its beautiful sandstone walls on the outside of the building are now grimy, dingy and, in some places, black.

In 2016, city leaders decided to do something about it.

"Three years later. It took a long time," said architect Maya Foty, who helped lead the project to reclaim the outside of City Hall.

There were a million challenges, from a lack of money to historical reviews to a requirement to learn where the original sandstone walls came from in case a big piece breaks off.

And while there is plenty around the Northwest, the stone is not local.

"At the time there was a train line that was started like in the late 1800's that went from Wyoming to Portland," Foty said.

That's right. Portland City Hall is made from sandstone that came from Wyoming.

Portland City Hall renovation
The sandstone walls on the outside of Portland City Hall are grimy, dingy, and in some places, black.
Pat Dooris, KGW

Some of the damage over the years came from water repellent meant to preserve the stone on the outside of City Hall.

Instead it preserved the water under the stone, which froze and thawed and eventually pushed out layers of stone till they fell.

Now that the work is underway, you'll see craftsmen carefully power washing the walls, not digging in too deep.

Others are using hand tools to gently scrape away the years of decay.

The company handling the work is Cedar Mill Construction and Matt White, the guy running the job, feels the pressure.

"Absolutely. I mean it’s an old building. So we want to do the best job we can and be as careful as we can," he said.

When it’s done, the building will have walls that are brighter than before, the windows will be fixed, and there will be a new eco roof, something the city requires of other downtown buildings.

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And there's a surprise awaiting all of us, hidden, but not buried in the outside walls.

If you look closely, you will find fossils from the sandstone quarry in Wyoming.

"There's different types, and some of them will be very small, but if you look you can see ... these little fossil shapes in the sandstone," Foty said.

"Is that an oyster shell?" I asked as she held up a picture of one such fossil.

"Yeah! Yes! It’s an oyster shell. Yes!" she said with a smile. An oyster shell fossil in one of the outside walls of Portland City Hall.

You will probably need to wait until the construction is finished in October to get a close look at the walls. But they’ve been there since 1895 and they are not going anywhere.