English: Inventor Nikola Tesla's Colorado Springs laboratory, where during the period 1899 - 1900 he conducted experiments in wireless power transmission. It contained one of the largest Tesla coils ever built, which could generate potentials of the order of 12 million volts at a frequency of 30 - 150 kHz, creating artificial "lightning bolts" reportedly over 100 feet long. The 142 foot telescoping "antenna" mast shown, made of concentric sections of pipe with a 30 in copper covered wooden ball on top, could be extended upward from a hatch in the roof. The lab no longer stands, it was torn down and sold to pay Tesla's debts in the early 1900s. This is a view of the front of the building, with the Union Printers Home (which still stands) visible in the background.