On the 20th anniversary of the fall of the Berlin Wall, BBC Mundo looks at barriers, which are still standing -- or have gone up since -- around the world.
From Northern Ireland to South Korea to Cyprus -- walls once embedded take on a life of their own -- dividing countries, social economic classes, and in some cases, family members.
Since the beginning of the year, Rio de Janeiro has been building walls around its favelas -- shanty towns on the hills around the city -- which will eventually be surrounded by concrete with a total length of 8.6 miles.
At the end of the 20th Century, Spain began constructing barriers in Ceuta and Melilla, to prevent illegal immigration from Africa. The people of Ceuta and Melilla have paid the price of living in a fortified city.
Designed as a temporary measure to keep fighting Protestant and Catholic communities apart, many "peace walls" are stills standing. The most recent wall was built as last year at a primary school north of Belfast.
The border between Mexico and the United States is 1,988 miles long. The US government has built a metal wall along a third of it, at an estimated cost so far of $2.5 billion to prevent the arrival of illegal immigrants from Mexico and Central America.