The 15-metre Swedish-ESO Submillimeter Telescope (SEST) at ESO's La Silla observing site in the southern part of the Atacama desert of Chile. Designed to observe at sub-millimetric wavelengths, SEST was built in 1987 on La Silla and decommissioned in 2003. ESO's 3.6-m telescope can be seen in the background. 2400 metres above sea level, La Silla was ESO's first observing site. Currently La Silla hosts the ESO 3.6-metre telescope, the New Technology Telescope (NTT) and the MPG/ESO 2.2-metre telescope.