“Town crier”, so a person verbally announcing various information (i.e. public notices), was present not only in the Middle Ages. In ancient Rome such a person was called as praeco (plural praecones).
Roman “shouters” announced the news mainly during nundiae, that is, on the eighth day of the week, when people working in the field came to the city to sell and buy products. It was a kind of weekend for the Romans. At that time, the capital was visited by many citizens, who at the time mostly also voted. Praecones thanks to that were able to give the news to a larger group of people.
Praecones announced city, public and court events, auctions, holidays and games. Possibly people who gave the news used a hand (as it was shown in the series “Rome”) to underline the words.