ok just to elaborate on the pic above, the square hole at the top (with green splash all over) is where the laser exits the building to mark the 0 degree meridian line.
the equipment producing the laser is towards the back (behind where I was standing where I took this shot) but you can see a faint green line in the pic that lines up to where the beam originates.
the equipment producing the laser is towards the back (behind where I was standing where I took this shot) but you can see a faint green line in the pic that lines up to where the beam originates.