The observatory was proposed in 1970 and officially opened in July 1975 with the commissioning of its 1.23-metre (48 in) telescope. The facility developed through German–Spanish cooperation in astronomy, and over time four additional telescopes were brought into operation. The
Schmidt telescope was moved to Calar Alto in 1976 from the
Hamburg Observatory at Bergedorf, where it had been completed in 1954. The observatory hosted the finish of
Stage 11 of the
2017 Vuelta a España cycling race (the stage was won by
Miguel Ángel López), having previously hosted stage finishes in
2004 (won by eventual race champion
Roberto Heras) and
2006 (won by
Igor Antón). Calar Alto was climbed on Stage 9 of the Vuelta (AUG 2021). ==Geography==