Getting 2d pictures with the correct perspective to look halfway decent with the 3D Parks is a real challenge. Since I can't use Google Earth to look at historical parks, I just find pictures that look similar to what I see from the pictures on
Ballparks of Baseball ? Your Guide to Major League Baseball Stadiums. My intent was to add backgrounds so that the parks con't look like they are floating in the sky. I am not all that happy with me results because some parks look like they are sitting on top a very high hill with the city beneath. If/when I can find perspective pictures that work better, I will up date the parks. I only put the background outside the left and right field fences as that is all you can see whilst playing the game. Also, I don't see any point in doing background for parks that don't show any sky whilst playing. e.g. Cleveland Municipal. I am going to post a link where you can download these parks. Then you can look at them from any angle you like.
https://drive.google.com/drive/u/0/my-drive