You need to take something like this to a specialist, if it is real it would be worth a pretty satoshi.
+1
Agreed, bring this to a coin dealer or have it verified through a grading service which also verifies authenticity. This is amazing condition considering the coins age. The fact that there is little to no wear and all of the details of the coin design are visible and not faded would make this highly sought after if authentic.
Dont wanna be a buzzkill, and its absolutely not worthless, but its not a very rare coin, even in its condition. Still a Nice coin though, and a nice start of a collection for sure!
https://www.vcoins.com/en/stores/coins_to_medals/37/product/constantine_i_ae3_city_commemorative__victory_on_prow__antioch_mint/83063/Default.aspx