An animation that shows the structure of matter in decreasing scale. Starting with a human hair (100 microns wide), then zooming into the hair cells, fibril structures, keratin molecules, carbon atoms, their nuclei, neutrons, protons, and finally the quarks.
CERN (European organization for nuclear research) has a complex of giant particle accelerators in Switzerland, which smash subatomic particles into each other (a.k.a. hadron colliders).
The largest of the colliders is contained in a circular tunnel, with a circumference of 26.7 kilometres (16.6 mi), at a depth ranging from 50 to 175 metres (164 to 574 ft) underground. Read more here and here.