The history of Volterra in Tuscany goes back to Neolithic times. It was an important Etruscan settlement and the Etruscan ruins can still be seen today.
In Roman times, it was an important town and again the Roman ruins including a Roman theatre are still very much evident.
Its important extended far into medieval times, the Renaissance and beyond.
But for two days in August: the 20th and 27th August, the town recreates a day in the life of the town in 1398. From morning to night , a Medieval city in the year 1398 is recreated throughout the historical centre with markets, open workshops, musicians, jugglers, commoners and nobles. The currency used is not the Euro but the "Grosso" (short for the "denaro grosso")
Presumably the liturgies in the churches will also be authentic.
Virtual Guide to Volterra
Official site of Volterra 1398