(After my old computer 'packed-in' and problems with Google Earth on my old laptop, I again have GE to work with!)
So, starting again from scratch I shall have another look at the Edinburgh grid introduced back in August/November 2012.
This time I started with the streets of central Edinburgh, using George Street as datum, using West Register House dome at the West end of Charlotte Square along George Street, through the statues at the junctions with Castle, Frederick and Hanover Streets and the Melville Monument in St Andrews Square at the East end. This also includes the recent erection of the James Clerk Maxwell statue at the east end of George Street. (My understanding is the Clerk part relates to the Clerks of Penicuik! More on that later when I'm more sure of the details!)
To the east of St Andrews Square the Bank of Scotland Headquarters (may be the Royal Bank, but I think that is at the top of the Mound!) dome sits on this alignment also. Calton Hill, where the road bends on the north side, but a good enough sight-line and finishes at the spire of the church at the top of Easter Road at the London Road junction. The same church I had on my original line which included Holyrood Palace/Abbey, Pilrig church and Pilrig House.
The orientation/azimuth from West Register House being: 73.28 degrees.
The line at ninety degrees is from the Tolbooth Church, the highest point in Edinburgh City(Arthurs Seat being outwith the city proper) down Dundas Street to Tanfield, and includes Assembly Hall(Church of Scotland), the statue atop the RSA(Royal Scottish Academy), and the line of the National Gallery, the statue at the junction of Hanover and George Streets, where lines intersect, azimuth:343.28 degrees.
Same with labels:
This third image shows the James Craig plan as is today:
I'll add an original image of the plan later!
The image below has an exact ninety degree line to the main axis, hence parallel to the other perpendicular, using Calton Hill Observatory, which needs investigation...