Contractor Specs, City of Portland, November 2007. “Salvage any metal horse rings encountered during curb removal. Reinstall horse ring assembly back at the same project stationing or as close as practical. If no new curb is constructed, deliver horse ring assemblies to the City’s Maintenance Bureau…”
In this instance the sidewalk/curbing appears to have been poured in 1910.
Some imaginative folks come up with uses that are very Portland..(image by Jan Landis). Of course, toy horses and circus animals have been used too.