From Madrid/Sur bus station ("Estación de Autobuses Sur"). The trip to Valladolid by bus takes about two and a half hours, subject to traffic conditions.
The Madrid/Sur bus station is also connected with Madrid/Barajas airport via undergroud (If you fly to Terminal 2 or Terminal 4, take line 8 from either "Barajas" or "Aeropuerto" to "Nuevos Ministerios" and then line 6 to "Mendez Álvaro"). T
ickets can be bought at the station, at the Alsa/Fernández-Res counters, and also on-line (www.alsa.es).
LINK ALSA Valladolid