There are many options for public transport within Rome with different tickets that you might use.
Type of Tickets:
Single ticket called "Biglietto singolo" which has a validity of 100 minutes for one trip only and for one person 1.5€ (for instance if your itinerary is bus+train or bus+bus or tram+ bus you can still use the same tickets within 100 minutes)
24h, 48h and 72h tickets which have a validity of the specified hours starting from the time you stamp the ticket - 7€, 12.5€, 18€.
🤔 Local Tips
In general, the old town can be fully visited by walking, indeed the main bus routes will bring you only near a monument, but you still need to walk a while before reaching it. As a general rule, you should use the bus or the subway only if the walking distance is above 40 minutes. The local buses are usually late due to the heavy traffic.
In Rome, there are roads and footpaths which are not very smooth so it might be a little challenging if you have a stroller or a wheelchair. I suggest in that case to take your time and allocate some extra time to move from one location to another.
🗒️ Note* Children up to 10 yo don't need a ticket to travel on public transports.
The tickets are sold at any vendor machine usually located in the subways or in a Tabacchi shop.
Public Transport