Denver Zoo's annual Zoo Lights kicked off Friday when Denver7's Mike Nelson flipped the switch.
Friday was particularly festive for once couple.
Nick and Mattie had their first date at Zoo Lights in 2011.
Under a rainbow of twinkly lights, Nick got down on one knee, surrounded by friends and family.
Mattie looked around, almost in disbelief, as Mattie smiled and popped the question.
Congratulations to the happy couple!