Whether stacked brick by brick, sculpted 
from corrugated metal, tubes, barbed wire, concrete or drywall,
a wall in its most basic form is a physical barrier.
Maybe, it supports a roof, protects a town from floods or separates your bedroom from the living room.
In isolation, a wall is not political.
But a wall can also keep people out, hold
people in, and almost always create some sort of divide.
In China, it's a defense system turned national landmark.
In Berlin, it was an infamous blockade.
And in America, it's an emblem of a
fiery divisive political debate. (Chanting: Build that wall!)
And sometimes when a wall is
built it eventually comes crashing down.
President Trump wants to build a
wall between the United States and Mexico.
But what will it really accomplish?
David Frye: A wall is only going to succeed in its purpose as
long as there is the political will to continue to guard it.
Trump (left corner): We have to be very
very strong on the border.
Trump (right corner): Border security to the
people of our country. Very important.
This is what some of the most famous walls in history can tell us about the U.S.-Mexico border today.
The history of walls can be traced back roughly 12,000 years and in the beginning they weren't nearly as socially divisive as they are now.
For most of history, walls were not controversial at all. A city is a community with walls.
The belief that well-marked boundaries reduced conflict
was more or less universal and arguably innate,
given the tendency even of animals to mark their own territories.
Territory, it's at the core
of so many wars in history.
In a territorial dispute, even Wall Street
got its name from yes, a wall.
It was originally built by the Dutch to protect
themselves from British colonists and keep Native Americans out.
The financial district has earned a reputation
of vast wealth – the center of capitalism.
It's become a symbol of a system that's
created more wealth than the world has ever seen.
But it's also earned a reputation of exploitation, deepening the divide between the haves and the have not's. And
that's been ingrained in the
area from its very inception.
In 1644, Governor Peter Stuyvesant
ordered his citizens to build a
wooden barricade on the northern
edge of the New Amsterdam settlement.
A few years later, the Peach Tree
War broke out between the Dutch and Native
Americans, and Stuyvesant ordered an expansion of
the wall to defend against future attacks.
It worked for a while but then
the British came by boat through the
southern end of the colony, took
the land and named it New York.
The wall itself was taken down by the
end of the century, but the name stuck.
In 1711,  Wall Street was turned into the city's official market for a very valuable resource at the time, slave labor.
And that is something that's weaved through many walls of the past no matter how emblematic they may be.
Today, you'll find one of
the most iconic, grandiose walls ever
built swarming with tour groups,
selfie sticks and even shopping malls.
People marvel at its sheer scale, which
took a lot of human power to build.
Generations, upon generations of Chinese peasants were dragged from their homes and in
dragooned into these forced labor crews
and required to build these walls.
And if they survive the very
difficult construction of these walls, they were
required to live by the walls in these desolate frontier zones.
Roughly 650 years ago the massive
project was ordered by the Ming Dynasty
to prevent invasions, protect the
Silk Road and preserve its culture.
Some say the building process began around 200 B.C., though most of that isn't standing today.
From 1368 to 1644, the Great
Wall was the world's largest military structure.
And it's so extensive, there's no
definitive record of how long it is
or how much it would cost
to build something like that today.
People estimate its length is
anywhere from 5,000 to 30,000 miles.
And something of that magnitude would obviously cost tens of billions of dollars or more.
These days tourists flock to the
landmark because of it's almost unthinkable size.
It's a very different attraction
from this next wall, the DMZ.
The demilitarized zone between North and
South Korea is no historical emblem.
To this day, its used as a
physical barrier to keep people from leaving.
And it stands a tangible symbol of the separation of governments, cultures and families who once lived together.
To us, we think of it as a symbol of this military conflict. To Koreans, it is a symbol of the division of our country.
The DMZ stretches roughly 150 miles long
and has divided communist North Korea from
its southern counterpart since an armistice was
signed during the Korean War in 1953.
The zone itself incorporates land
from both sides of the
territory line and it's decorated with barbed wire fences, abandoned  bridges, tunnels guard posts, highly
trained army squads and artillery units.
These are two countries that in 70 years of division have just gone completely different directions in terms of their economies.
You can't see it, to
be honest, at the DMZ.
You can however see it,
in the difference between the soldiers.
They do send some of
their tallest, fittest North Korean soldiers.
Because of chronic hunger and malnutrition, they're still
quite a bit smaller than the South Korean soldiers.
But the area between
the fences is surprisingly peaceful.
Since nobody can enter, the lack of
human interference has allowed wildlife to thrive.
The wall at the DMZ wasn't the only barrier to separate the communist block of the Soviet Union from the West.
After World War II, there was a
big territorial question: which superpower would control Europe?
In the 1945 Potsdam agreement, the U.K., U.S. and Soviet Union decided to split Germany down the middle.
Berlin fell in the eastern half of Germany.
but the U.S. still wanted to keep a presence in the
capital city where it helped topple the Nazis.
It became an island of Western influence and
a safe haven for people escaping Soviet oppression.
The East German government ordered
the wall's construction in August 1961.
On the dividing line between West and East Berlin, this was the sight that greeted Berliners on the morning of Sunday, August 13.
East German police and military units were busy sealing the entire length of the city's dividing line with barricades and obstruction.
The Berlin Wall came to symbolize the Iron Curtain dividing Europe.
The 96 mile wall cost about $25 million to build at the time which comes out to about $200 million today. It was 12 feet high and layered with concrete and brick, topped with barbed
wire and used more resources with
302 armed guard towers and 55,000 landmines.
The Berlin Wall in many ways served as a prototype for a lot of the controversial walls of the 21st century.
Here was an early attempt to build
a wall which was backed by technology.
You know, the Berlin Wall was a double wall with a kill zone between the inner wall and the outer wall.
Germans went to great lengths to
get around, over and through the wall.
They floated over in hot air balloons, flew by zip lines, tiptoed on tight ropes, swam across the Teltrow
canal and crawled through hand dug tunnels.
Nobody knows for sure how many people were able to escape, but one estimate puts it at 5,000.
And at least 140 people died trying.
The Berlin Wall was a rarity in history.
It was a wall constructed to keep
people from escaping rather than from entering.
Mr. Gorbachev, tear down this wall. (applause)
In 1989, the very people the Wall
was designed to divide tore it down.
A historic moment a moment that will live forever. You're seeing the destruction of the Berlin Wall.
The next year, the region was
reunified as the Federal Republic of Germany.
And today on the last remnants of
the wall, you'll find a stretch of murals.
It's art that's a symbol of
the explosion of creativity and self-expression,
a privilege that generations of people
in East Berlin were deprived of.
Today, there are new walls
popping up all over the world.
Norway, Hungary, Thailand and more countries are turning national boundaries, once imaginary lines on a map into tangible physical barriers
to stop the flow of immigration and combat cross-border crime.
And then there's the West Bank wall.
The West Bank is a complex, controversial area of land.
In 1967, with tensions high, a war that lasted only six days left Israel with control over more land in the region.
When it came to the West Bank, Israelis started building homes.
Now nearly 50,0000 Israelis live in the West
Bank in what are referred to as settlements.
And there is still a lot of tension.
There are three million Palestinians
that also live there today.
Israelis see it as an important religious land.
But Palestinians see the Israeli's
presence as an invasion of theirs.
In 2000, an Israeli leader visited the Temple
Mount, a holy area for both Muslims and Jews.
Just after, there was a
Palestinian uprising called the Second Intifada.
And the Israeli government started constructing a wall
two years later, at the height of the conflict.
From 2000 to 2005, nearly 1,000 Israelis
and more than 3,000 Palestinians were killed.
While there have been other clashes since, the death
toll on both sides has significantly decreased since 2002.
Certainly Israelis credit it with increased
safety in Israel and in the territories.
The barrier stretches roughly
400 miles and cost $1.6 million per mile.
First, it was a combination of earthen
ramparts or trenches in some places concrete wall.
It also involves about 680 various roadblocks which in
2018 are now about 705 permanent roadblocks.
The two sides don't even use
the same words to describe the structure.
Israelis call it an anti-terrorism obstacle,
while Palestinians call it an Apartheid wall.
I've traveled back and forth between the wall in Bethlehem and the West Bank and Israel and there's
a lot of graffiti on the Palestinian side
of the wall, and some of it highly controversial.
But interestingly a lot of it in
English which says that the Palestinians are
trying to communicate to the United
States what the wall means for them.
Halfway across the world, the United States is debating a multi-billion dollar extension for a 1,900 mile long wall of its own.
These prototypes made from concrete, tubing and
metal are standing along the border right now.
They're not protecting a
community from natural disasters.
These walls are made to block
the flow of people and drugs.
It's a proposed solution for a problem
that some say just isn't that urgent.
There's been a radical shift
in why walls are being built.
Border walls nowadays would not be
effective as it turns to military invasion.
In a world of artillery and airplanes, 
a wall isn't going to do much.
In March 2017, Customs and Border
Patrol asked for design submissions with
a pleasing color and texture on
the north side of the barrier.
This wall is a lightning rod for controversy
among politicians, academics and probably your family dinner table.
But there's another set of people that don't
agree on what the southern border should look like.
And they have a pretty significant say
in the future of the wall – architects.
To some it's just another job, but to others
it's a line they're not willing to cross or design.
Architects are ethically charged with not only
serving clients and serving them well but also
being guardians of the public realm and
of the communities within which those buildings sit.
And it seemed to us that that
construction of this massive wall over such a
large area was symbolic it was divisive
in how it was being put out.
And it wasn't bringing the community together, it wasn't
supporting the public, it was doing exactly the opposite.
The U.S.-Mexico border isn't the first wall to stoke fear about what lies on the other side, and it won't be the last.
But looking back at other famous walls in history, it makes me wonder how this time will be remembered.
I don't think it'll be remembered 50
or 100 years from now, to be honest.
We tend to overrate our own importance historically.
But when you study ancient history, not many things are remembered 50 or 100 and certainly not a thousand years later.
Of course, that all depends on if the wall is actually built.
