Last week, by an odd twist of my schedule, I found myself visiting two sites in two hemispheres that each focus on apartheid. One is well known: Robben Island, the prison off Cape Town, South Africa, where Nelson Mandela was jailed for 18 years. The other is hardly visible: Maticni Street in Usti nad Labem, a gritty industrial town in the Czech Republic, where locals built a block-long wall in 1999 to separate an enclave of the Roma (gypsies) from the Czechs across the street. Robben Island, a seminal training ground for anti-apartheid forces, was a maximum-security facility from which no political prisoner ever escaped. The wall at Usti, a seven-foot-high noise barrier with several open gates through it, prevented nobody from moving anywhere. Robben Island endured for decades. The so-called "wall of shame" lasted about a month. Some say the story out of Usti -- near the border with the former East Germany, and only a decade distant from the Berlin Wall -- loomed larger in the press than it deserved to. But did it? Apartheid comes in many forms. But it always starts from a premise that "they're different from us," and that they need to be separated from us, often forcibly.