The Large Hadron Collider is the coldest place in the known universe

The LHC at CERN uses superconducting magnets cooled by liquid helium to -271.3°C — just 1.9 degrees above absolute zero, colder than the average temperature of outer space (-270.45°C). The LHC has a circumference of 27 kilometres and accelerates protons to 99.9999991% the speed of light. When two proton beams collide, the impact point briefly reaches a temperature 100,000 times hotter than the centre of the Sun. The machine simultaneously hosts the coldest and the hottest human-made environments — separated by about 10 centimetres of metal.

Source: CERN Technical Documentation; Evans, L. (ed.), The Large Hadron Collider (IOP Publishing, 2009)