The Bernard Lyot telescope (TBL) was built at the beginning of the 1980s. This massive device comprises a heavy 65-ton mount that allows the telescope's eye to point towards the sky in all directions. Despite this imposing appearance, the TBL mirror, with its 6.56 ft (2 m) in diameter, remains modest in size when compared to those at the ESO observatory in Chile (26.9 ft/8.2 m) or Keck in Hawaii (32.81 ft/10 m). However, the TBL remains the largest telescope in mainland France and the only one to allow spectropolarimetry, the study of stellar magnetic fields.