Just off the main inner ring road around 800m northwest of Leuven train station, this world-famous, highly automated brewery offers mostly group tours, though individual visitors can join weekend visits at 1pm (in Dutch) and 3pm (in English). Buy tickets from the tourist office or through the website as far ahead as possible.
It's not unusual to find that a pre-booked group tour has extra space that you can sign up for via the website – choose according to the flagged language of the available tours.