The city centre is walkable. The main monuments, markets, and eating districts are all within about 30 minutes on foot of each other. The White Tower, Aristotelous Square, the Roman Forum, the Modiano market and Ladadika form a loose cluster that you can cover comfortably in a day without using any transport at all.
Ano Poli requires a 20–30 minute walk uphill from the lower city. Taxis are cheap and plentiful; call one or find them at stands around Aristotelous and Eleftherias Squares. City buses cover the broader metropolitan area including the university and the outer suburbs. The city's metro opened in 2023 with a central line running under the city from east to west — a smaller network than Athens but useful for getting between the station, the centre, and the eastern suburbs. Tickets are available at stations and cost the same as a bus ticket.
For the airport and day trips to Halkidiki, taxis or rental cars are the most practical option.