When someone at your office approaches retirement after 30 or so years of working, you don't give him a card, a cake, a few short words to make him feel better about waking up to empty days ahead, and then send him off into the sunset of his life. That's just not right. This man deserves a grand retirement party that will make him feel like a highly-decorated and bemedalled general! He's got his own war stories to tell and by golly, give him that by throwing a retirement party that will blow his socks off!
This is quite a feat to achieve not to mention the hush-hush way of organizing the big day but if you do this coming from a place of service and generosity towards someone who has spent his long years working with you, the priceless smile and glint of tears on his face will make all the effort you put into this so much worthwhile.