Iron Curtain
Physical barrier

“Behind me stands a wall that encircles the free sectors of this city, part of a vast system of barriers that divides the entire continent of Europe. From the Baltic, south, those barriers cut across Germany in a gash of barbed wire, concrete, dog runs, and guard towers. Farther south, there may be no visible, no obvious wall. But there remain armed guards and checkpoints all the same – still a restriction on the right to travel, still an instrument to impose upon ordinary men and women the will of a totalitarian state.”

– Ronald Reagan at the Tear down this wall! speech in 1987, which was written by Peter Robinson

The Iron Curtain took physical shape in the form of border defences between the countries of western and eastern Europe. There were some of the most heavily militarised areas in the world, particularly the so-called " inner German border " – commonly known as die Grenze in German – between East and West Germany.

Elsewhere along the border between West and East, the defence works resembled those on the intra-German border. During the Cold War, the border zone in Hungary started 15 kilometres (9.3 mi) from the border. Citizens could only enter the area if they lived in the zone or had a passport valid for traveling out. Traffic control points and patrols enforced this regulation.

Those who lived within the 15 kilometres (9.3 mi) border-zone needed special permission to enter the area within 5 kilometres (3.1 mi) of the border. The area was very difficult to approach and heavily fortified. In the 1950s and 1960s, a double barbed-wire fence was installed 50 metres (160 ft) from the border. The space between the two fences was laden with land mines. The minefield was later replaced with an electric signal fence (about 1 kilometre (0.62 mi) from the border) and a barbed wire fence, along with guard towers and a sand strip to track border violations. Regular patrols sought to prevent escape attempts. They included cars and mounted units. Guards and dog patrol units watched the border 24/7 and were authorised to use their weapons to stop escapees. The wire fence nearest the actual border was irregularly displaced from the actual border, which was marked only by stones. Anyone attempting to escape would have to cross up to 400 metres (1,300 ft) before they could cross the actual border. Several escape attempts failed when the escapees were stopped after crossing the outer fence.

The creation of these highly militarised no-man's lands led to de facto nature reserves and created a wildlife corridor across Europe; this helped the spread of several species to new territories. Since the fall of the Iron Curtain, several initiatives are pursuing the creation of a European Green Belt nature preserve area along the Iron Curtain's former route. In fact, a long-distance cycling route along the length of the former border called the Iron Curtain Trail (ICT) exists as a project of the European Union and other associated nations. The trail is 6,800 km (4,200 mi) long and spans from Finland to Greece.

The term "Iron Curtain" was only used for the fortified borders in Europe; it was not used for similar borders in Asia between socialist and capitalist states (these were, for a time, dubbed the Bamboo Curtain). The border between North Korea and South Korea is very comparable to the former inner German border, particularly in its degree of militarisation, but it has never conventionally been considered part of any Iron Curtain.
punctuation:no_comma, length_constraints:number_paragraphs[3], language:response_language[Polish]