Bologna Guglielmo Marconi Airport: For speed, take the Marconi Express to Bologna Centrale: 7 minutes, about €12.80 one way. It is expensive for the distance and queues can be long. The sensible budget choice is bus 944 to the centre/Centrale: roughly 20–25 minutes and about €4. A taxi is worthwhile only with luggage or a group; expect roughly €20–25 to the centre.
Bologna Centrale: This is the arrival point that matters: high-speed trains put Florence about 37 minutes away, Milan about 65 minutes, Rome about 2 hr 20 min and Venice about 2 hours away. The historic centre begins a 15–20-minute walk south; take a local TPER bus if your hotel is beyond Piazza Maggiore. Check the platform suffix carefully—platforms such as 3, 3 Est and 3 Ovest are not interchangeable.
Autostazione di Bologna: The intercity coach station is by Porta Galliera, at the north end of Via Indipendenza. It is an easy 15–20-minute walk to Piazza Maggiore and close to Bologna Centrale; do not pay for a taxi unless you have mobility or heavy-luggage reasons.