  The history of the IRSOL observatory is closely related to Second Solar
Spectrum observations. Already in 1963 Brueckner observed scattering
polarization in the CaI 4227A line. In 1996 the Hanle effect in the quiet
chromosphere was measured for the first time in Locarno using the same spectral
line. Since 1998 the ZIMPOL system, a polarimeter allowing unprecedented
polarimetric precision, has been installed at IRSOL and been constantly
upgraded to state-of-the-art technologies thanks to the close collaboration
with the Institute of Astronomy in Zurich. It allows to measure the faint
signatures of various scattering polarization effects. A brief historical
summary of observations related to polarization at IRSOL is given.
