Tucked into the small town of Annawan, Illinois, there’s a little diner that has been quietly winning hearts for three decades. For anyone hunting a genuine Illinois day-trip stop, the Purple Onion makes a strong first impression before you even open the door. She opened the Purple Onion three decades ago and has been shaping its warm, homey character ever since. Why This Detour Is Worth TakingSo, is a little diner in Annawan really worth pulling off the interstate? For Illinois families, couples, and day-trippers craving an easy, affordable outing with an outsized payoff, the Purple Onion checks every box.