After the “Shootings Court” or as it is also named the “Executions Court”, keep going until you will find a metal staircase leading you downstairs. You will be inside the Dromos and the Atrium of the elliptical ramp. Go along the ramp and after a few minutes you will reach the diametral ramp, created by Bonifacius IX, Go on top of it and you will be in the Room of the Urns.