I'm kicking off the parks I volunteered to help with by sharing Congress Street Grounds in Boston. While not all that historically significant, the park was decent looking from an architectural standpoint. Add in the view of Boston Harbor and it's a neat park. It was home to the Boston Reds in 1890-91.
Google Drive link to Congress Street Grounds
Information is limited here so I did end up taking some liberties, but made the most educated decisions possible. For example, I had figures for the total size of the site but not exact dimensions. There is repeated commentary from newspaper articles of the time stating that home runs were routinely hit over the left field wall, but that it was nearly impossible to hit them elsewhere. Given that and a suggestion that the left field wall was less than 250 feet away from home, I fit my estimated playing field dimensions into the known overall site dimensions.
Just a note here that I have only been creating 3D models for a few months and this is the first park I'm brave enough to share, so I'm certainly open to any feedback. Games are running smoothly so far, but I haven't done a lot of testing yet.