Berlin Wall, one of the most well known modern walls, is a symbol of division in Germany.
In 1961, Berlin was divided right down the middle by a 27-mile-long wall, designed to stop people moving east to west. Even though in places it was only 11 feet tall, it was heavily guarded. Over the nearly thirty-year-period it stood, more than 100 people were killed trying to cross the wall, but 5,000 managed to make it.
In 1989, the Berlin Wall fell after an East German Politburo officer lifted travel restrictions early. The wall still stands in parts of Berlin to remind the city of its past.
In Belfast, Northern Ireland, "peace walls" still divide the streets.
In 1961, to try and stop violence and riots in Belfast, walls were built across the Northern Ireland city, to separate Catholics who wanted unification with the rest of Ireland, from Protestants, who supported British rule. There are now almost 60 walls across Northern Ireland. Despite an agreement being reached on governing Northern Ireland in 1998, called the Good Friday agreement, many of the walls were actually erected afterwards.
They're not stopping riots anymore, but the first wall wasn't knocked down until 2016. There's a plan to have them all destroyed by 2023 to end divisons in the country. But by May 2018, few walls had been removed.
In Lima, Peru, the city is divided by a wall called "the Wall of Shame," which cuts through four neighborhoods, separating rich from the poor.
Lima's wall is six miles long, 10-feet high, and covered in barbed wire. Construction began in 1985 to separate wealthy communities from the poor. It was erected in response to migrants settling down in the hills of Lima, after fleeing from violent clashes in southern Peru.
The wall continued to expand as richer neighborhoods tried to cut off the poorer ones. It was permitted by local officials, who provided police to act as guards.
According to Megan Janetsky, who interviewed locals for The Atlantic, some of those living on the wealthy side of the wall had forgot it existed. But it wasn't so easy for those in the poorer communities who had to commute several hours every day to get around the wall.
In Syria, the city of Homs's "loyal" and "disloyal" suburbs were divided by a wall built by the government.
This 10-foot-wall was first erected in 2012. It took two months to build and it's less than a mile long. The heavily-guarded wall was built to separate Alawite districts, who are loyal to the government, from the Sunnies, who are viewed as disloyal to Syria's regime.
Nicosia in Cyprus is divided by a wall.
This wall is made up of sandbags, barrels filled with dirt, cement walls, and barbed wire. It's 120-miles-long and while it divides the city, it also runs the length of Cyprus. On one side live Christian Orthodox Greeks and on the other there are Muslim Turkish residents.
It was first built in 1974, after Turkey invaded the island. The wall, which actually has a buffer zone, narrows to a few metres in the city. The two sides of the island share sewage and electricity systems, but that's about it. In 2003, restrictions about crossing the wall were relaxed, but passports are still needed to cross from one side of the island to the other.
Melilla and Ceuta, two autonomous Spanish cities, are cut off from Morocco by walls.
The fence, which divides the city of Melilla from Morroco, was first built in 1995 and has been defended with blades, alarms and, at one time, pepper gas. The wall was built to stop illegal immigration. Ceutas also has a nearby 20-foot fence covered in barbed wire. Since the walls have been erected, the number of immigrants getting into the cities has fallen, but it's still a problem for the two autonomous cities.
Morocco has also cut itself off from the Western Sahara, with the world's oldest barrier.
The berm, first built in 1980, divides Morocco from the Western Sahara and is made from sand and barbed wire. There are also minefields. It runs between Morroco, Algeria and Mauritania. According to The Guardian it's also built from "rumours, half truths, and bluster." It was built to hold off the Saharawi people, who have been fighting Morroco since 1975, when Morroco claimed the area.
And then there are the walls dividing countries, like the United States' border with Mexico.
The border between the two countries is almost 2,000 miles long, and 700 of those are walled or fenced off. There are gaps in the walls, most commonly for rivers. But US Border Patrol also uses hot air balloons to get a bird's eye view, and drones and cameras to provide constant surveillance. That isn't enough for President Trump though who wants an "impenetrable, physical, tall, powerful, beautiful" wall.
In September 2019, White House officials said the installation of more fencing would begin in earnest, with a target of building 500 miles of the new border by the end of 2020.
Between North and South Korea there's a heavily militarized border that's separated them since 1953.
The 160 mile long and 1.5 miles wide border and demilitarized zone, separating North and South Korea, was established in 1953. The actual fences are topped with barbed wire, the zone has has mines, and it also has the most military at a border anywhere in the world.
Israel cuts itself off from Palestine along the West Bank with what it calls an "anti-terrorism" wall.
Israel began building this 425-mile-long wall in 2002 in response to Palestinian suicide bombers, causing 130 deaths in one month alone. While Israeli officials call it it's an anti-terrorism wall, Palestinians say it's an "apartheid" wall.
In 2004, the International Court of Justice called the wall illegal, since it ran through occupied territory.
Israel has recently built a wall at its border with Lebanon.
In 2018, Israel began building a 30-foot wall which, when finished, will run for 80 miles, to block off Lebanon, saying it was erected to protect residents from attacks. But building the wall prompted Lebanon to file a complaint to the UN, because it says the wall enters its territory in some areas.
And Israel also has a wall along its southern border with Egypt.
A 150-mile-long fence, which was completed in 2012, divides the two countries. It's 16-feet and topped with barbed wire, as well as being equipped with motion sensors. It was built by Israel to stop illegal immigration and military attacks. It was so impressive, India sent a delegation to analyze the border. According to the Jerusalem Post, the US also closely monitored the radar equipment Israel uses along the wall.
Egypt built a wall along its border with the Gaza Strip, but it was partially destroyed by militants.
This wall, which was built to cut off Gaza, was blasted down in 2008 by militants. It's thought that about half of Gaza's residents used the destruction to cross the border. Egyptian guards erected chain fences and barbed wire to reseal the border as soon as they could.
European countries, like Hungary, have joined in, mostly to stop the flow of refugees.
Hungary built a 100-mile-long border wall to define its borders with Serbia and Croatia. Stretches of the fence will give electric shocks to anyone who tries to climb it. It's also covered with surveillance equipment. Along with the cost of patrols, and building transit areas, the wall cost Hungary about $1.1 billion.
India's border with Pakistan has a bloodied history.
The border between these two countries has had a chaotic history, with a lot of bloodshed. Between the two countries runs a 450-mile-long barbed wire fence called the Line of Control. It often floods the area with light at night. The border is also heavily guarded, but it still has problems. In 2019, the Indian government started a project to build 14,000 bunkers for Indian families to live in to protect them as bullets fly over the border.
And India also built a wall to cut itself off from Bangladesh.
Beginning in 1986, a wall was built that runs 2,500 miles and is topped with barbed wire to separate India and Bangladesh. India built it to try and stop smuggling, illegal immigrants, and terrorist attacks. Between 2003 and 2013, 1,000 people were killed at the border, shot by India's border security.