A hundred meters beneath the Franco-Swiss border spins humanity's largest machine: the 27km Large Hadron Collider. Above ground, CERN welcomes visitors free in Renzo Piano's stunning Science Gateway (2023). This is where Tim Berners-Lee invented the World Wide Web in 1989 (the first server is on display) and where the Higgs boson was announced in 2012. Superb hands-on exhibits for families; tram 18 runs from central Geneva in 25 minutes. Guided facility tours open online weeks ahead and vanish in minutes.