The head office is located at Bezová 1658/1, Praha 4. See the map.
The nearest stops are U Staré pošty, Branické náměstí (bus) and Pobřežní cesta (bus and tram). Buses leave mainly from Smíchovské nádraží (yellow B line) or from Budějovická and Kačerov (red C line).
The bus connection can be found here http://www.dpp.cz/en/.