Authorities have set up a temporary jail facility to house those arrested during the convention - a city-owned warehouse on Denver's northeast side.
The jail is filled with chain-link cells that measure about five feet by five feet and have razor wire surrounding the top openings.
CBS Station KCNC made an unannounced visit to the temporary jail earlier this week. Their tape showed one sign on a wall reading, "Warning: Electric stun devices used in this facility."
Groups planning marches, concerts and other events during the Aug. 25-28 convention dub the center "Gitmo on the Platte," for the nearby South Platte River.
"Very reminiscent of a political prisoner camp or a concentration camp," was how Code Pink's Zoe Williams described the facility to KCNC correspondent Rock Sallinger.
On Friday a small group of people showed up outside the warehouse with signs complaining about the jail and how they compare it with history.
One sign called it a gulag.
The Denver sheriff's office, which operates city and county jails, insists anyone taken to the center will be there only a few hours while they're fingerprinted, issued a court date and released after posting bail. Others will be transferred to facilities designed for longer detentions.
"Of course if the numbers are overwhelming, that's all going to be out the door," said Capt. Frank Gale, a sheriff's spokesman. "If we're inundated with a bunch of civil unrest, it doesn't matter how well we prepare. If we get severe numbers it's going to take us forever" to process those in custody.
Lindy Eichenbaum Lent, senior advisor to Mayor John Hickenlooper, said the warehouse was formerly used to store election equipment and construction was still underway to convert it to a processing center. She said the center was an effort to allay fears that those arrested would spend several unnecessary hours waiting to be processed.
Hickenlooper's office said police will ask people to voluntarily comply with their orders before arresting anyone. "The city does not anticipate the need for widespread arrests," the mayor's office statement said. But it noted "the intention of some organizations to deliberately get arrested."
The American Civil Liberties Union and the People's Law Project have been talking with the city about giving attorneys access to detainees. The city said attorneys can meet clients in court, not at the facility.
ACLU-Colorado legal director Mark Silverstein said city officials told him detained protesters will be taken by bus to the facility, about two miles northeast of downtown. Those who are unable or refuse to post bail will be taken to a downtown city jail to await a court date.
Silverstein said warehouse cells won't have running water, bathrooms or telephones. Gale said deputies will escort anyone needing those services.
"It's just ridiculous, the thing looks like a dog pound," said Mark Cohen of the protest group Recreate-68 Alliance. "Even if you only put dogs in there, people will be complaining about it. I think you ought to have the Red Cross and Amnesty International come take a look at this thing."