The City and County building lit up for the holiday season Friday at the 9NEWS Light the Lights celebration.
More than 585 energy-efficient LED lights and 2,000 feet of LED rope lights transformed the structure into one of the most popular holiday lighting displays in the region.
The tradition dates all the way back to 1926, and is the biggest lighting event from Denver to the West Coast.
Hundreds of people gathered in Civic Center Park for singing, hot chocolate and the countdown to the light up.
The lights will turn on each night through January 22.
And be sure to mark your calendars for the 9NEWS Parade of Lights, which returns to Denver next weekend.
Sparkling lights, marching bands, giant balloons and colorful floats will take to the streets on Dec. 2 at 8 p.m. and Saturday, Dec. 3 at 6 p.m.