I love to see art pieces in public spaces – they often liven up a place and generate conversation. Below are a few interesting installations found in the U.S. and Europe, both permanent and temporary, in quite a range of styles and materials.
Streetscape sculptures in downtown Portland, Oregon
Stainless steel piece incorporating running water in the Rose Test Garden of Portland, Oregon
Bronze elephants in the North Park Blocks of Portland, Oregon
Salvador Dali elephant along the Thames River in London
Series of stone sculptures in a park in Caunes-Minervois, France
Core-ten steel lobster in Woolwich, Maine
Wind-activated piece in the deCordova Sculpture Park, Lincoln, Massachusetts
Giant typewriter eraser in the Olympic Sculpture Park, Seattle, Washington
Jellyfish in Elm Park, Worcester, Massachusetts
Hand-woven banners cover a footbridge in Elm Park, Worcester, Massachusetts
Barrel Monster is erected for a festival in Raleigh, North Carolina
Photos in Massachusetts and Oregon by Alice Webb
Photos in Washington, Maine, North Carolina, and European countries by Nancy Novell
Land Perspectives 
Those are really fun sculptures. They all seem to have a sense of humor, which is a good departure from the over serious ones so much in the past. Both kinds are worth while, but really, going to the park should encourage relaxation–and what better way than with humor.