The Castillete Óptico or the Optical Tower, originally named the “Elephanta’s Telegraph”, was erected in 1850 in order to house the first optical telegraph, then under the umbrella of the Astronomical Observatory. Its location in the highest part of the Retiro Park enabled the Levante and Andalusia lines to be connected visually. Between 1868 and 1888 it belonged to the Madrid City Council, although it no longer fulfilled its original purpose, since the optical telegraph system had been replaced by electrical telegraphy in 1857, the year in which the lines were dismantled. On November 2, 1888, it was transferred to the recently created Central Meteorological Institute, which was its official headquarters until 1963.