Rashi on Bamidbor 19 (4) says:
אל נכח פני אהל מועד [HE SHALL SPRINKLE THE BLOOD] TOWARDS THE FRONT SIDE OF THE APPOINTED TENT
He stands at the East of Jerusalem and must direct his gaze straight towards the entrance of the Heichal at the time of sprinkling the blood (Sifrei Bamidbar 123:2; Yoma 68a).
Is there a modern diagram showing the line of sight from the location where the blood of the Poroh Adumoh was sprinkled to the entrance of the Heichal as described in the above Rashi?