Bilbao Turismo (tel: (94) 479 5760/70; website: www.bilbao.net/bilbaoturismo), the local tourism organisation, organises two guided walking tours on most Saturdays and Sundays throughout the year. One of the tours covers the Old Town, taking participants back in time to Medieval Bilbao with its cobbled streets, charming corners and squares, and traces its development through the centuries. This tour starts at the tourism office by the Arriaga Theatre. The second tour covers the Ensanche-Abandoibarra area and explores Bilbao's architectural and urban development from the 19th century to the present, taking a look at the throbbing heart of a city where tradition and modernity converge. This tour starts at the tourism office next to the Guggenheim Museum. Both tours last for about 90 minutes. Reservations are not necessary.