Memorial to the "Flosser" who used to float rafts of logs along the river Neckar northwards to the cities along the Rhine. Some parts of Amsterdam are still standing on wooden piles from this region.
The river didn't have a strong enough flow normally, so they would build a dam and wait until there was a good head of water and then released it all at once.
I'm frequently in awe of what some men did through history to support their families.
Edit:
The memorial is here, on the Neckar River Cycleway.