At the very crest of the hill, you will find the Old Observatory, the only building designed by James Craig left in the city; it was completed in 1792.
James Craig was not known to design buildings.  
mnli hypothesis: James Craig was not known to design buildings.   premise: At the very crest of the hill, you will find the Old Observatory, the only building designed by James Craig left in the city; it was completed in 1792.