One of the things that I have noticed about UK cities is that they all seem to have, at their heart, some neat geological feature. In Edinburgh's case, it is a volcano. Edinburgh castle is built atop a batholith that cooled during the Mississippian (~340 Ma old).
Features of this volcano are present throughout the landscape. This includes Salisbury Crags (or Craigs, I have seen it both ways). The crags are columnar basalts which are interpreted to be a sill associated with the Mississippian volcanism. Anyway, following are some of the pictures I took within the city of Edinburgh. If our major cities incorporated more geology, I think I wouldn't avoid them.
Below is a complete picture of Edinburgh Castle, including the batholith peeking out beneath the castle:Below is a close-up of the castle. The basalt is a bit clearer in this photo:
The Salisbury Crags (taken from a tour bus). At some point, I would like to come back and go for a hike on the trail around the Crags:A close up of the columnar basalt at the Crags (also taken from a bus):