With the Iron Curtain solidly drawn around it, Estonia was struggling to make tourism ends meet in the decades after World War II. That is, until both its Soviet overlords and sightseeing industry found the perfect solution: They would outfit the increasingly accessible nation with a luxury hotel that unwittingly brought together a vacationing crowd and the U.S.S.R.’s most vigilant gatekeepers.

At the classy Hotel Viru in the city of Tallinn, well-heeled travelers arranged business transactions, gossiped, and traded information about what lay beyond the Soviet bloc. Between 1972 and 1991, the imposing hotel in Estonia’s capital was filled with foreign travelers and Estonians visiting from abroad. Boasting a foreign currency exchange, Western alcohol and goods, and a bustling restaurant, the hotel entrapped visitors into occupying themselves within its premises rather than seeking entertainment outside.

This was all in line with the plan of the KGB agents who listened in to every syllable and watched every step taken from their listening room hidden on the secret top floor of Hotel Viru. Unsuspecting guests were oblivious to the fact that their ashtrays and dinner plates came with electronic bugs, the sauna taped each conversation, and, of course, their hotel rooms were outfitted with secret microphones and cameras.