At a conference that began in Potsdam between Stalin, Truman and Churchill in July 1945, the Allied leaders used pre-war provincial boundaries to carve up the country into British, French, American and Soviet sectors. The first three merged into West Germany; the USSR's portion became East Germany. Barriers began to divide families and friends. The purpose of the frontier was ostensibly self-defence, but its real aim was to stem the economic migration depleting Eastern Europe's most productive nation.
The frontier hardened over the next generation. "You may encounter a sense of simmering resentment when you brightly announce your imminent departure to the West," a 1989 travel guide warned tourists helpfully. The book was published shortly before East Germany was about to celebrate its 40th anniversary; instead, the people refused to suspend their disbelief any longer, and the country ceased to exist. These days, the boundary between the German Federal Republic and the "Democratic" version has been defused, and is now pursuing a new life as a tourist trail.
To visit the relics of repression, only so recently abandoned, is both chilling and thrilling. No guidebook will yet direct you to the relics of conflict, but Cold War memories are being reheated at a number of locations all along the frontier.
The cauterisation of normal channels of communication slowed the pulse of places in West Germany close to the frontier. Schnackenburg found itself at the tip of a finger of land protruding into East Germany. Overnight, a busy village at one of the crossing points of the Elbe river became a backwater.
For 40 years, this absurdly pretty assembly of neat redbrick houses has perched on a landscape straight out of a Constable painting. The ferry link across the Elbe has been restored. Schnackenburg now lures tourists into stopping off with the Grenzlandmuseum, a lumbering barn of a house. The loft beneath the terracotta tiles contains a kitsch manifestation of East German frontier officials, a kind of "Ken and Barbie-defect-to- the GDR" tableau.
The Fulda Gap was the location at which a Warsaw Pact invasion was anticipated. With Frankfurt only 50 miles away, the base at Point Alpha was the closest point to West Germany's industrial heartland. It lies on one of the most beautiful stretches of the former frontier, where no-man's land snakes over rolling hills and drifts across valleys. This was part of the American zone: the 11th Armored Cavalry Regiment had the task of defending democracy.
Countless tons of concrete and acres of barbed wire were used to prevent escape from the high-security prison that was East Germany. A restriction zone was established three miles inside the eastern frontier. Trees were cleared, and progressively more brutish obstructions imposed upon the landscape: dog patrols, electrified fences, and heavily armed soldiers surveying the ensemble from watchtowers.
The legal frontier was actually a few yards further to the west, beyond the final barrier, marked by a series of posts.
As recently as June 1989, the border police from the West were issuing warnings, pointing out "the mistaken assumption that the area between the border demarcation line and the border fortification is a No-Man's Land... those persons who violate GDR territory - either accidentally or intentionally - run a very serious risk."
The Border Museum Rhon, which was recently created at Point Alpha, explains the intricacies of oppression. The newly liberated East Germans led the campaign to create a memorial at the site. Servicemen from both sides have returned to inspect the site, and to wander around the ghostly fortifications that were off-limits to them.
In the visitors' book, Leland L Cogdill Jr observes: "It was 722 days of hard work, defending the frontier of freedom." Meanwhile Geoff Walden has a more crisp analysis, writing: "We won the Cold War."
The border swerves around from Point Alpha to head east. The most significant cities form a matching pair on either side of the old frontier: Coburg and Sonneberg. Prosperous Coburg, which fell in the western side, was the home of Prince Albert, who married Queen Victoria and sired the Saxe- Coburg-Gotha line for the British crown. The contrast with the sterility of Sonneberg is intense. Here, the shape of the frontier resembles a fist punching into the belly of Bavaria. One knuckle comprised the city of Sonneberg and surrounding villages, which became depopulated as the Cold War went on.
Residents were removed to East Germany's industrial heartland. Stefan Ruger, who runs his family's small hotel in the city, recalls the Grenzoffnung in November 1989 - when the barrier came down. Stefan's first reaction was not to head West, but to see what he had been missing in his own region: "We went around all the villages to see what they were like."
A brass band straight out of Bavaria was warming up in this small village when I arrived. But only half the oompahs were Bavarian - the rest resounded from the Thuringen contingent of the municipal band. A narrow stream has long divided the lande of Bavaria from Thuringen.
What was a mere bureaucratic inconvenience became a community-shredding impasse after the war. Modlareuth became known as "Little Berlin".
The name of the German-German Museum - which features archaic Cold War military hardware, and now covers much of the village - is intended to emphasise the nonsensical geopolitics that placed this quiet corner of central Europe on the ideological cusp between Moscow and Washington.
Of all the relics along the line, it is the most moving, for the sheer inhumanity wrought by 40 years of madness. Just a decade later, the band is back in tune.
Getting there: to cover the frontier, the easiest way is to fly into Hamburg and out of Nurnberg, but this is more expensive than a no-frills return flight to Berlin. Virgin Express (0800 891199) begins flights on Wednesday from London Stansted to Berlin Schonefeld for pounds 76.50 or more, and KLM's Buzz (0870 240 7070) starts flying from Stansted to Berlin Tegel on 4 January - fares from pounds 60.
Attractions: The Grenzlandmuseum (00 49 58 40 210) is in the Fischerhaus at Schnackenburg. Open 10am-4pm, Mon to Fri, 11am-5pm, Sat and Sun, entry DM5. Border Museum Rhon, near Rasdorf (00 49 66 51 91 90 30), 10am-4pm daily (longer in summer), entry DM3. Pension Ruger, Gleisdamm Strasse 2, Sonneberg (00 49 36 75 70 26 84). German-German Museum, Modlareuth (00 49 92 95 13 34), 10am-6pm daily, entry DM3.
Further reading: Along the Wall and Watchtowers by Oliver August, just out (HarperCollins, pounds 17.99).