This London Planetree (Platanus x acerifolia) is on the corner of SW Main & Park. As noted in the Portland Parks & Recreation guide, it has a trunk containing large, warty bumps. Planted in 1880.
I just noticed it on my way to the car after visiting the Portland Art Museum. If you're in town, visit the Museum for its current "Wild Beauty: Photographs of the Columbia River Gorge, 1867-1957" exhibit. Wonderful, large-scale photos from the original large negatives. Photographer Carleton Watkins is the highlight. He invented his own large-scale camera to obtain negatives large enough to capture the vastness of his subject. His entire camera outfit weighed more than 2,000 pounds, which he hauled around in a boat, setting up a darkroom tent on the beach as he worked his way up and down the gorge. You can see the gorge from many viewpoints, as unspoiled wilderness, or as a sight for commerce, industry and tourism. It's all there in black & white (and occasional color).