Borromean rings are a configuration of closed curves in three-dimensional space in which no two individual curves are linked, but all three are linked jointly. Removing any of three causes the other two to fall apart. Forms of the symbol are common in heraldry (they are named after the House of Borromeo in Italy, on whose coat of arms they appear), have been used as a sign of the Christian Trinity, and in the U.S. appeared on the label of Ballantine beer for over a century.
But is it actually possible to make Borromean rings with three circular links in the real world?