 The tower had two floors and a mezzanine . On the first floor was the famous Sundial Room or Meridian Room , which was initially an open loggia . Pope Urban VIII had it enclosed and it was subsequently decorated with long sequences of frescoes painted between 1580 and 1582 by Simon Lagi and the two Flemish artists Paul and Matthijs Bril . Today the tower has paintings by Cristoforo Roncalli and Matteino da Siena . 
