The Collaborative International Dictionary of English v.0.48:

Sistine \Sis"tine\, a.[It. sistino.]
   Of or pertaining to Pope Sixtus.
   [1913 Webster]

   Sistine chapel, a chapel in the Vatican at Rome, built by
      Pope Sixtus IV., and decorated with frescoes by Michael
      Angelo and others.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Sistine Chapel
    n 1: the private chapel of the popes in Rome; it was built by
         and named after Sixtus IV in 1473