I was meeting no one and saying nothing in my room, unless I was speaking in my sleep.

I had no idea the KGB was monitoring me with microphones and hidden cameras. It would be many years before I discovered that I was, apparently, worth spying upon.

It still seems absurd. It was December 1988. Summer in Australia.

All my life I had celebrated the Australian summer by catching waves and lying about on a beach. But here I was resting my head in deepest winter in the dying days of the Cold War, though no one quite knew yet that the Soviet Union would soon expire in shocking haste.

I had come by overnight train from Moscow to the city of Tallinn on the Baltic Sea, capital of what was then the very restive Soviet Republic of Estonia. It was a journey that would imprint itself on my memory.

As the train pulled out of Moscow, it streamed into a landscape that might have been a film set for Dr Zhivago. As evening came down, we entered a forest, every limb of every fir tree laden with fresh snow.

Passengers stood in the train's corridor, silently watching the countryside until the light faded and night settled. It was beautiful and moving, but it was a very long way from the southern summer, and the mood felt bogged in melancholy.

I was accompanied by a friendly, earnest young man who worked, he told me, for the Soviet news agency Novosti. He was also a committed member of the Communist Party and had named his baby son after his personal hero, Vladimir Ilyich Ulyanov, the party's founder known as Lenin.

I was a guest of the Soviet Union under "glasnost", the radical new policy sanctioned by the chairman of the Presidium of the Supreme Soviet, Mikhael Gorbachev.

Glasnost means "openness", and meant permission to discuss politics and social matters – something denied to Soviet citizens for 70 years.

Glasnost was an astonishing departure, still feared by many ordinary people who remembered family or neighbours disappearing in the night for as little as making jokes about Communist Party officials during the Stalin period.

Intellectuals and the more daring, however, were embracing their new freedom with giddy excitement. In the Baltic states, I would discover, you could barely hear yourself think in the poets' salons, where the most vigorous discussions took place.

"When you have taken your first breath of fresh air, it is impossible to stop breathing," cried one prominent Estonian poet when I visited a salon and wondered why everyone seemed to be shouting.

The Soviet embassy in Canberra had been instructed to offer an Australian journalist a visa to witness all this new restructuring (perestroika) and openness (glasnost).

When asked where I wished to travel, I named the three Baltic states – Estonia, Latvia and Lithuania – that were kicking up a fuss about wanting independence from the USSR, something that seemed at the time little but a pipedream, and close to treason.

I discovered the dire nature of the economy on my first day in Moscow.

Having been told before flying from Australia that the most useful currency in the Soviet Union was cigarettes, I had packed several cartons of soft-pack duty-free Marlboros in my luggage during a stopover in Singapore before boarding a down-at-heel Aeroflot plane.

After the early blue-sky summer in Australia, the Moscow airport was a cold concrete bunker, and despite a paucity of travellers, I was held up for what felt like hours, with no sign of my suitcase.

When it was finally delivered and I had travelled the snowy highway into Moscow, there to be accommodated in one of the 3000 rooms of the gigantic Hotel Rossiya next to Red Square, I decided to arm myself with a packet of smokes in case I needed to bribe someone.

Every carton was missing, treasure purloined by customs officials.

Needing to purchase a new supply, I was bewildered by the business of currency exchange. The official rate at the hotel was a risible $US2 for a single Soviet rouble.

Stumbling in shock to the street, I was instantly surrounded by blackmarket kids offering 10 roubles for $1 (the current 2017 market rate is around 60 Russian roubles for $1). The reality, it turned out, was that I didn't need roubles.

Universal shortages meant there was almost nothing you'd want to buy. I was pointed to the beryoska store in my hotel: a shop that took only hard currency (no roubles allowed, and thus no locals) and which stocked tacky souvenirs, chocolate, liquor and Western cigarettes.

In my hotel corridor sat a large stern lady whose official duty was to separate all guests from their room keys before they were allowed to leave the floor. I came to assume my room was searched every time I left.

By the time I got to the Hotel Viru in Tallin, Estonia, I should have assumed I was being monitored. But my guide laughed and assured me the old stories about the KGB bugging and filming foreigners were fabricated.

Keen to discover a little of how life was lived in that bleak world, I settled on a method of meeting "locals". All those black market kids offering money exchange and wanting to buy my leather jacket became a rough detour around the control of my guide.

I took to handing out cigarettes if they would get me past the officials who were the hotel gatekeepers and the "mafia" toughs who hung around the hotel's exits, extracting with menaces "tribute" from the cashed-up black market kids.

My occasional escapes were made in the night, when my guide had gone to bed, and once or twice a carton of cigarettes got me into apartments where several generations of families lived in a few small rooms, confirming how pinched Soviet lives had become in the Baltics.

My black market contacts regularly warned me to avoid any conversations in my hotel rooms. "KGB," they said.

Paranoia, I figured, but I was usually dead beat by the time I got back to my room anyway.

Twenty-five years later, in 2013, the owners of the Hotel Viru, which had, once Estonia got its independence, been privatised, decided to reveal a secret.

A room on the hotel's 23rd floor was finally opened to the public. It had been locked and preserved since the night in 1991 that its inhabitants, a team of KGB spies, had fled.

And there were the listening devices and wrecked radio equipment on steel racks and the film equipment and the ancient typewriters for transcribing overheard conversations. There were even ashtrays with smokes butted out a quarter of a century before, and a green cot.

You can still visit this strange little museum on the 23rd floor of the Hotel Viru.Those listening devices were linked to 60 guest rooms in the hotel, in phones, light fittings and flowerpots.

The rooms had holes bored in their walls for the business of filming what was going on inside. All very Maxwell Smart.The KGB's Hotel Viru spying operation had been going on since the hotel was built in the 1960s, and the prime targets were foreign business people ... and Western journalists.

God knows what blackmail might have occurred, though most of the listening, apparently, was to mine Western business secrets and to find out what travelling journalists might be writing.

The Hotel Viru's secret room on the 23rd floor is unlikely to have been unusual. In the southern summer-northern winter I stayed at the Viru in Estonia, a lieutenant-colonel in the KGB named Vladimir Putin was stationed in Dresden, East Germany.

His tasks have never been clearly explained, but most intelligence analysts agree that even in far-away Dresden, a KGB officer's job would have including monitoring foreigners and trying to compromise them.

Putin's trajectory since then has been ever upward, and the Russia he came home to – and eventually to lead – has changed immensely since 1988, just as spying methods have become vastly more sophisticated than the old Maxwell Smart days of the Hotel Viru.

Did Putin ever really leave the KGB as he gained power, handing over the most serious jobs in the new Russia to former KGB operatives?

"There is no such thing as a former KGB man," he said famously in 2004, with no smile. For some reason, that long-ago summer in the Cold War came to mind in the days after Donald Trump denied a secret report – unsubstantiated, of course – that he had been filmed with prostitutes, on Putin's orders, in a hotel in Moscow.

Couldn't have happened. Could it?