To live in East Germany under the German Democratic Republic (GDR) was to live under constant surveillance.
At its height, the government presided over a huge network of informers (estimates place this number at one for every six citizens).
Many people would discover after the wall fell in 1989 that they had been betrayed by friends, family and partners.
The items in this list shed some light on the regime. The huge number of cameras, most ingeniously concealed within everyday objects, offer an insight into its extreme paranoia.
10. GDR athletics flag
This flag was flown at the European Track and Field Games in Split, in the former Yugoslavia, in 1990 - the last time the GDR competed as a nation.
It's signed with the names of most of the team members and realised $704 in an Agon Sports World auction in Kassel, Germany in 2006.
9. 'East German Soldier Jumping Over'
Photographer Peter Leibing captured the defection of East German soldier Conrad Schumann in 1961.
Schumann later told reporters that he had been upset by the sight of a child being dragged back into the East while trying to flee and made his decision in a split second.
It became one of the most famous images of the era, appearing on the covers of magazines and newspapers around the world. This print realised $1,404 at Bassenge in Berlin in 2010.
8. Sniper rifle
Among the more shocking artefacts from the regime, this sniper rifle was allegedly used to shoot people attempting to jump the wall.
It sold for $750 at Orange Coast Auctions in California in 2012.
Over 100 people were killed trying to cross the border. Today their names are marked on a series of white crosses placed on the banks of the Spree.
7. Room observation outfit
This room observation outfit would have been used to spy on supposed enemies of the state by allowing officers to peer through a concealed camera.
The Stasi could gain access to any building and were well practised in surveillance.
Homes would be broken into and bugged in order to determine the occupants' allegiance.
In some cases, items would be moved or changed very slightly in a concerted effort to make the person believe they were going insane.
The lot realised $3,319 at Westlicht Photographica Auction in 2013.
6. Matchbox camera
This miniscule camera is hidden inside a box of matches and dates to 1955.
It likely was built as a prototype. It sold for $2,808 at Auction Team Brekker in 2006.
5. Briefcase camera
This briefcase contains two cameras, allowing agents to covertly take multiple-angle photographs when opened.
It made $3,000 at Westlicht Photographica Auction in 2012.
4. Cigarette lighter camera
This time a lighter houses the camera mechanism with the lens poking out of the bottom. This particular specimen is believed to be unique.
It sold for $12,778 at Auction Team Brekker in 2005.
3. Ballpoint camera
This is one of the most sophisticated spy cameras of its era.
It was produced as a combined effort of the OTS, the technical wing of the Stasi, and the Czech secret service.
A shutter hidden at the top is fired simply by twisting the cap. Inside a 6mm wide film strip allows for 10 photographs.
It realised $24,279 at Westlicht Photographica Auction in 2011.
2. Jane and Louise Wilson's Stasi City
Stasi City is a 1997 exhibit made up of photography and video by sisters Jane and Louis Wilson.
The title refers to the warren of offices in Berlin that housed the state's officials and secret police.
This photograph, from a project of the same name, shows a section of corridor in the complex.
The sisters explained: "We were thinking of a prison as a very confined space, but also of the confinement of being in East Berlin, of not being able to go those few feet further into West Berlin. Imagine that kind of restriction."
This print made ?�25,300 ($41,221) at Christie's London in 1999.
1. Erich Honecker's limo
Erich Honecker led the GDR from 1971 until the state's dissolution in 1989.
He remained fully committed to the regime's excesses right up until the very end, when thousands were streaming across the border.
He used this ZIL 115 limousine to shuttle between his various appointments. In addition to the standard features (cigarette lighter, electric windows etc), it also comes equipped with a siren and flashing lights.
It was purchased directly from the old GDR transport pool in the months following the fall.