Ice Castles created with icicles and ever-evolving ice formations at Silverthrone in Colorado have been attracting lots of visitors.

Every day at the Ice Castles is unique and different. The ice formations are constantly evolving, depending on the amount of water added at night, the night time temperature, and snowfall, a statement on the official Web site of the Ice Castles reads.

Built by Brent Christensen, the Ice Castles at Silverthorne consists of man-made walkways, tunnels, and arches of ice with no supporting structures, some reaching up to a height of 30 to 40 feet (9 to 12 meters).

Christensen first built Ice Castles in 2003 in the front yard of his home in Utah. He built his first large Ice Castle at a local resort in 2009-10 winters that attracted about 10,000 visitors. The number of visitors further increased to over 25,000 the following year.

The recent Ice Castles by Christensen in Colorado have been erected with 20,000 tons of ice frozen vertically on over an acre of land. The ice formations are illuminated at night by 200 compact florescent lights and provide unique opportunities for tourists.

Scroll down to view the pictures of Ice Castles during the day and illuminated in the night.