Nice piece, in patina. A large silver coin from the 1st century BC.
Obverse: Head of Alexander the Great with Ammon's horns to the right, behind it Θ, below legend MAKEΔONΩN.
Reverse: Treasury, mace and curule chair, above legend AESILLAS Q, all within a wreath.
Silver, diameter 28.5 mm, weight 16.31 g.