In the northern hemisphere, it's the season for building things out of snow and ice — including enormous castles and buildings. Here are some of the most impressive.
The first ice palace, built in St. Petersburg, Russia for Empress Anna Ivanovna as a part of the celebration of Russia's victory over the Ottomans in 1739-1740.
It was designed by Pyotr Yeropkin with a garden filled with an elephant, birds and trees, all of them made from ice.
(via State Russian Museum/Wikimedia Commons)
The Indian New Deal Ice Palace near Lake Bemidji, Minnesota, 1934
(via Wikimedia Commons/Franklin D. Roosevelt Presidential Library and Museum)
The Carnaval de Québec ice palaces, Québec, Canada
(via Carnaval de Québec)
The 1986 Saint Paul Winter Carnival ice palace in Saint Paul, Minnesota
(via Saint Paul Almanac)
The world's first ice hotel, the ICEHOTEL in Jukkasjärvi, Sweden, opened in 1990. Every furniture its is made of snow and 100,000 tons of ice taken from the nearby river.
(via bjaglin, azedkae, Oceans of Lilim, Jörgen Bengtson and Wikimedia Commons)
The SnowCastle of Kemi in Finland, the biggest snow castle in the world, rebuilt every winter since 1996 on an area between 13,000 and 20,000 sqm with 65ft (20 m) high and 3,280 ft (1000 m) long walls.
(via Kemin LumiLinna/Facebook and Elissa Ernst/Flickr)
The Ice Hotel with a small chapel for weddings, near Quebec City (Hôtel de Glace), Canada, made with 15,000 tons of ice, opened in 2001
(via Chensiyauan/Wikimedia Commons and Hôtel de Glace/Facebook)
Huge ice buildings, some of them with colored lights at the 22th Harbin Ice Lantern Art Festival in Harbin, China, December 2002
(via AP/Li Yong/XINHUA and Cancan Chu/Getty Images)
The copy of the first ice palace built in 1739 in Palace Square, St. Petersburg, opened in 2006
(via Dmitry Lovetsky/AP)
Tourists view ice buildings and a maze in the Grand Ice and Snow World at 23rd Harbin International Ice and Snow Festival in Harbin, China, January 2007
(via Cancan Chu/Getty Images)
The Mario-inspired castle in Michigan Technological University's Winter Carnival in Houghton, Michigan, 2010
(via Wikimedia Commons/MIT)
The ICIUM Wonderworld of Ice in Levi, Finland, opened in December 2010. There are ice and snow sculptures and buildings in an area of 2.5 acres (1 ha).
(via ICIUM)
Colorful buildings made from blocks of ice at Harbin International Ice and Snow Festival, Harbin, China, January 2012
(via AP/Andy Wong)