Arthur's Seat is an ancient volcano and is the main peak of a group of hills that form Holyrood Park.  It is located to the east of Edinburgh. It is mentioned in legends surrounding King Arthur like Y Gododdin. 

It is mentioned in Recollections of a Tour Made in Scotland by Dorothy Wordsworth when she says, "We set out upon our walk, and went through many streets to Holyrood House, and thence to the hill called Arthur’s Seat, a high hill, very rocky at the top, and below covered with smooth turf, on which sheep were feeding." 

Plae of residence of the Koh-i-Noor diamond and Timur ruby today.

Last place the Koh-i-Noor Diamond and Timur Ruby were in 'India'.