Utrecht’s Dom Church has offered a free concert every Saturday at 15:30 since 1971. This concert series stems from a long church music tradition which can be traced back to the year 1023 when the Romanesque Dom Church dedicated to St. Martin was completed. Gregorian chants were heard, every three hours each day and night. Today concerts are usually attended by 400 - 1,000 people. Upon exiting the church, visitors are asked to leave a 'recommended donation' of €5, so it's not exactly free, but quite cheap by Dutch standards.
