Sofia Airport (SOF) is 10 km east of the centre with direct flights to most European capitals. The metro M4 line runs from Terminal 2 to the centre in 20 minutes for the price of a normal ticket — by far the easiest way in. Taxis from the official rank at the airport are inexpensive but stick to the regulated companies (OK Supertrans is the standard).
Trains arrive at Sofia Central Station north of the centre. The line from Belgrade goes via Niš and crosses the border at Kalotina; the line south to Thessaloniki goes via Kulata. Domestic services connect Sofia with Plovdiv (1.5 hr), Varna (7 hr), and Burgas (6.5 hr).
Long-distance buses use the Central Bus Station next to the train station. Service is dense to neighbouring countries: Skopje, Niš, Bucharest, Istanbul, and Thessaloniki all have multiple daily departures. Domestic buses cover everywhere a train does not, often faster.