At the Tate Modern in London, the Shibboleth 2007 ran from October 2007 to April 2008. It was a 548 feet long crack on the floor which addresses "a long legacy of racism and colonialism that underlies the modern world." Source.
It begins as a crack, but deepens and snakes across the floor of the Turbine Hall. At some points, it is four feet across. In the first four weeks of the exhibit, 15 people were injured.
One incident: "We saw the first poor victim, a young woman who went into it with both feet up to just below her knees. She had to be dragged out by her friends. . . .Unbelievably, as we watched to see whether she was OK, an older woman deliberately stepped on it (she later told us, amazingly, that she thought the crack was painted on the floor) lurched forward and landed on the ground. She had a sore wrist to show for it." Source.
Here is a video of people looking at the exhibit and here is a video of the exhibit from beginning to end.
In 2006, the Tate Modern exhibited five corkscrew slides. The biggest slide was 182 feet long with a drop of 88.5 feet. Four legal claims followed.
Also in 2007, Urs Fischer spent ten days and $250,000 to build a 38 by 30 foot and eight feet deep crater in the Gavin Brown Enterprise Gallery. The crater is surrounded by a fourteen-inch ledge. A sign warns, "THE INSTALLATION IS PHYSICALLY DANGEROUS AND INHERENTLY INVOLVES THE RISK OF SERIOUS INJURY OR DEATH." The crater is titled You. Source.