franeymoon wrote:I heard the charge was €20 for 3 hours.
Not quite. To guide people within the city walls of the Old Town, one must be licensed by the local guide association. And by being a member of the association, a guide must charge listed prices. That means any tour up to 2 hours is a roughly 500kn (about 70€) charge, minimum. Add another 200kn for going over 2 hours plus of course any entrance fees.
That doesn't mean some non-licensed guide won't offer to guide you around the old town, but know it is illegal, although this really doesn't affect the client.