All three emergency services were called when a man climbed up a 40-metre crane under the cover of darkness.
A police helicopter, firefighters and paramedics all attended when a white beam of light was seen moving around on the top of the crane in Oxford in the early hours.
By the time police arrived at 04:15 GMT, the torch had been turned off but helicopter thermal imaging equipment revealed a person on the tower.
The man eventually climbed down.
Specialist rope access teams were also requested to attend the construction site in Banbury Road, Summertown.
Fire station manager Darran Hookway said: "The man suffered no injuries and the rescue teams did not need to climb the tower crane to bring him down."