T.E.C. (Transports en Commun) have an impressive modern bus network.
There is an information office and ticket office in Place St. Lambert open Mondays to Fridays 8.45 to 18.00 and Saturdays 8.45 to 12.00 (Tel: 04/222.05.61).
You can get tickets for single journeys (€1.60), cards for 8 journeys (€5.80) or season tickets (€28/month; €220/year). For the latter, you will need a passport photo.
From the City Centre, buses 58 and 48 serve Sart Tilman. Both leave from the Opéra, but only the 48 stops at les Guillemins. The journey takes 35 minutes on average for the 48 and 20 minutes for the 58. During the day, expect to wait between 4 and 10 minutes between buses.
For more details, go to the TEC website.
SNCB (Société Nationale des Chemins de Fer Belge) offers various reductions and benefits for travelling in Belgium and Europe. Don't hesitate to contact SNCB to find out more details: +32 4 229.26.10 or here.
Here are some of the most common reductions: