This board is approximately 18 inches across. 
 
It appears to have a handle/hole in the middle, and the back is solid. Appears to be pressboard, but well made and very solid. There were no pegs or anything with it, so I'm not positive that it's a game board. 
 
Even if you don't want to buy it, but know what it is, let me know - I'm curious!
 
Looks new/unused. Very unique and would make a great table top, wall decoration or maybe a game!