A good Recessionista is always on the lookout for free days---those gleeful occasions on which some of the most well-trod institutions waive their admission fees. As dedicated as I am, I'm also often the forgetful one who hears about all the free fun from colleagues after it's already passed. Thanks to a Denver Post article, I marked my calendar with upcoming free days around Denver. Here's a quick roundup of seven great spots: Aurora History Museum: Admission is always free. More information: auroragov.org. Children's Museum of Denver: Admission ranges from $5.50-$7.50. Check out the museum for free the first Tuesday of every month, from 4 to 8 p.m. More information: mychildsmuseum.org. Denver Art Museum: Admission is typically $5-$13 for non-residents and $3-$10 for residents. General admission is free the first Saturday of each month. More information: denverartmuseum.org. Denver Botanic Gardens: Admission is $8-$11.50 but will increase slightly in May. Check out the gardens for free on Feb. 15, April 22, July 22, Aug. 25, Sept. 26, and Oct. 28. More information: botanicgardens.org. Denver Museum of Nature & Science: General admission ranges from $6-$11. Check out the museum for free on Feb. 21, March 1, April 18, Aug. 8, Aug. 30, Sept. 13, Sept. 19, Oct. 3, Oct. 8, Nov. 14, and Dec. 6. More information: dmns.org. Denver Zoo: Admission ranges from $5-$12 (depending on the time of year). Check out the zoo for free on Feb. 16, Oct. 13, Oct. 21, Nov. 7, and Nov. 13. More information: denverzoo.org. Hudson Gardens & Event Center: Admission is $2-$5 from May to October. Through April, guests choose their admission price. More information: hudsongardens.org.