A roman mask is an item in Evony TKR (The King's Return).
Roman Mask is one of the collection items in the exhibition for the Art Hall. It is one of four parts in the Mask Hall. After the set is completed at three stars, you can trade additional Roman Mask fragments for gold.
The description of Roman Mask in Evony TKR says:
Masks from different cultures. The important exhibits in Mask Hall.
Roman Mask is known to potentially be obtainable from opening Artwork Fragment Chest V and Artwork Fragment Chest VI. The links for each item are below:
Note: This list may be incomplete.