No, the park you speak of is Forest Park - St. Louis' answer to Central Park or the Common, on a much larger scale. It was the site of the 1904 World's Fair and is the home of the free
St. Louis Art Museum, the free and highly regarded
Zoo, the
Missouri History Museum (which incidentally, I think has one of the most fantastic facades in the city), the
MUNY Opera House/Amphitheater, and where that rehearsal dinner was - the
Jewel Box. There's a lot more to it that I couldn't possibly describe in one post, but it's really one of the greatest parks in the country.
Citygarden is a very new sculpture park, that's an exhibit in landscape design in it's own right, and includes a small cafe very obviously inspired by Mies. I'd compare it to a very little brother of Chicago's Millenium Park, or a Post Office Square with a bit more sculpture and a little less activity.
Here are some pictures of Forest Park:
St. Louis Art Museum
Missouri History Museum
World's Fair Pavillion and Government Hill (children play in the fountain when it's nice out)
Nathan Frank Bandstand outside the MUNY
Jewel Box Conservatory
Citygarden