In a dark hallway, visitors to the house are greeted by a wooden box where paper requests for information about prisoners and denunciations of neighbours and work colleagues were once deposited.
A ground floor exhibition details KGB crimes and in the basement cells that once held prisoners have, after many years, finally been opened to the public.
"The main reaction we get is shock," Aija Abens, one of the guides, told me.
"Some people come then decide not to set foot inside. Some people break down in tears. That's when we realise that they or their relatives must have been held here."
Thousands of Latvians were interrogated and tortured in the building, some of them put to death behind its walls, and Abens is visibly moved as she describes the former execution chamber.
"It's right by the door to the yard. A truck would be parked outside with the motor running to mask the noise.
"Then the body would be put in the back and driven away," she says.
Later the KGB began killing their victims elsewhere and the execution cell was converted into a kiosk where agents could stock up on cigarettes.
"We get visitors from Russia who think it's all made up, but we also get Russian visitors who say it has opened their eyes," Abens told me.
They have even had some visitors who, she believes, once worked here.
"We showed the KGB staff canteen on one tour and a visitor said: 'Yes, but the food was good'. How could you know that unless you were part of the staff?"
A couple of floors above, the atmosphere is very different.
The corridors have been freshly painted a dazzlingly white and art installations invite visitors to consider abstract concepts of state power and totalitarianism. Several focus on the 60,000 Latvians who were deported to Siberia on the orders of Stalin, most in 1941 and 1947, and many of whom never returned.
One piece, Latvian Suitcase, is among the most powerful. It highlights a question those exiled were forced to consider: What would you take if the KGB gave you two minutes to pack?
Suitcases, letters, lucky charms, teddy bears, even a parcel of sand from a spouse's grave are strewn around a large room. All the objects on show are original, each item once packed in haste by people who later found their way back home against the odds.
Another installation uses a pair of men's German army boots to explore the extraordinary life of Merija Grinberga, a woman from a renowned Latvian high society family who exchanged her high heels for heavy boots in 1944 to rescue items from the national museum slated for destruction by the Soviet Red Army.
Studying one of the artworks is tourist Melanie Carter, from Florida.
"Until I arrived in Latvia I knew very little about the history. I'm impressed by the effort, imagination and creativity that has gone into this," she said.
"It's an extraordinary project, given the building was used for such a horrifying purpose."
And it is this blood-soaked past that is proving to be major headache for public officials trying to find a future use for the "House on the Corner" - nobody wants to move into this otherwise prime, city-centre location.
"Its dramatic history makes it unattractive. Probably offices are best suited to it," says Baiba Strautmane, who manages the building for the State Property Agency.
"There have been rumours of hotels, but that's unlikely."
Pressure is growing for the building to become a permanent museum, although Latvia already has the Museum of the Occupation.
Knuts Skujenieks, a writer and former political prisoner who was once held here accused of "anti-Soviet" activity, is among those who support the museum idea.
"It's true the building's reputation isn't very good, but I believe the city needs it so it remembers," he said.
"You can't escape history. I can't remember where everything was, but I want to see the cell where I was held."
CHECKLIST
Getting there: Emirates connects to Stockholm via Dubai. From there, ferries go to Riga
- AAP
