Milwaukee County Stadium opened in 1953 when the Boston Braves moved to Milwaukee. The Braves played there from 1953 until they moved to Atlanta after the 1965 season. Milwaukee went without its own major league team until 1970 when the bankrupt Seattle Pilots moved to County Stadium to be the Milwaukee Brewers. The Brewers played in County Stadium from 1970 until 2000 until they opened Miller Park in the old stadium's parking lot in 2001.
Most of the old County Stadium field is now occupied by Helfaer Field. Helfaer is a little league sized ballpark that is used by local youth teams. On Brewers game days, the park is open to anyone to play catch or have a quick game.
Located in the third base walkway/concourse of Helfaer Field is the marker for County Stadium's home plate. Apparently, there is also a marker beyond Helfaer's left field that marks the approximate landing spot of Hank Aaron's 755th and final home run. I don't know if this was dedicated after my visit in 2005, or if I was just unaware of it. Either way, I don't have any pictures of that marker.
Located just to the north of the home plate marker is a memorial to the Milwaukee Braves. Its a really nice piece made of black and grey granite. It shows the players from the first and last Braves games and also marks the Braves' only World Championship. This is still Milwaukee's only World Championship, a seven game series which was actually clinched in Yankee Stadium. Interestingly, the Yankees returned the favor in 1958 by taking game seven at County Stadium to win the 1958 World Series.
It's a really nice set up and well worth visiting if you're going to a game at Miller Park. Although the stadium saw only 43 full seasons, it was the site of three World Series and many home runs by the great Hank Aaron.
See these images and more at StadiumPage.com.