Toronto police gave reporters a tour Tuesday afternoon of a controversial makeshift prison that held hundreds of G20 protesters but is now empty and being cleaned up.

The temporary facility on Eastern Avenue, set up in a former film studio in the city's east end, had a capacity for 500 prisoners. Police estimated about 1,000 people were detained there at various times between June 24 and 28 during the G20 protests.

Staff Supt. Jeff McGuire led the tour with Supt. Michael Farrar, unit commander of the facility, where large cages lined against a long wall. In each holding cell designed to hold 10 to 20 people, there was only a bench and a portable pottie with no door.

Prisoners were given toilet paper if they asked for it and they could sleep if they wanted to, McGuire said.

Video cameras were placed on the ceiling about every five metres to monitor prisoners from the time they entered to the time they left. Video surveillance was excluded in the portable bathrooms and search rooms, police said.

"Very few" people were strip-searched, Farrar said.

Farrar said the intention was always to release most of the protesters without charges because they were detained for a breach of the peace, which is not a criminal offence .

"The No. 1 purpose for most of the arrests was to re-establish peace on our streets," Farrar said.

Seven hundred detained protesters were released without being charged. The remaining 200 or so were sent to other jails.

The charges include arson, for torching a police car, and endangering life, police said.