PHOENIX -- Tent City is celebrating 18 years of operation as a jail facility for Maricopa County Sheriff Joe Arpaio's inmates.
It's been controversial since it opened in 1993.
More than 500,000 have served their time in Tent City, living in canvas tents during the extreme heat of the summer and the occasional freezing temperatures of winter.
While Tent City has been a target of criticism since day one, Arpaio says the conditions there are similar to the housing situation for U.S. troops serving in Iraq and Afghanistan.
Inmates say it's rough going at Tent City, but many of them work in air-conditioned facilities. They also have the opportunity to volunteer to work off-site as part of the sheriff's chain gangs.
"It's not somewhere you would want to be, especially during the summer," said inmate Virginia Muños. "The good thing is we have the day room that's open 24 hours."
Tent City is the largest facility of its kind in the entire country.
"Tent City has served as a model program throughout the entire nation as an economical, safe and successful way to house a growing inmate population," Arpaio said in a news release.
Males make up most of the Tent City population, but a female Tent City was added in the late 1990s.
A party to celebrate the milestone will be held Wednesday afternoon. During the event, Arpaio will unveil a special granite marker, a gift from the business community and Fulton Homes, that will stand in the exact spot where Arpaio first announced the opening of Tent City 18 years ago.
Some protesters from various Latino and immigrant communities said they would be at Tent City in the morning to protest the celebration. They compare Tent City to concentration camps, calling the treatment of inmates there "inhumane and unnecessary," especially during the extreme heat of the summer.