This 1907 photo shows the original Multnomah County Courthouse on the block bordered by SW 4th and 5th Avenues, Main and Salmon Streets. This is the dome pictured in yesterday’s post. Instead of leveling the site and starting from scratch, apparently the new courthouse building was constructed in stages, around the old building. Maybe it was something like 1) build 1/3 of new building while still using old building, 2) move everything from old to new, 3) tear down old, and 4) finish construction of new.
This is the 4th Avenue elevation; the posts and chains in the foreground still surround Lownsdale Square.
Vintage Portland 
Very reminiscent of the Oregon Capitol of the time. However, the Capitol was constructed after this building, so I wonder if there was a design choice in Salem that was influenced by the courthouse.