Edinburgh

Edinburgh is the capital city of Scotland, located at the Firth of Forth, the underground is composed of volcanic rocks. The city even has a volcanic cone named Arthur’s Seat in the southeast. The rest of the city has numerous low hills, which were mostly formed by glacial erosion. In other words, the geology is not suitable for natural caves, but there are numerous artificial underground structures as a result of centuries of history, like in most big cities of the World. But those structures were rather recently opened to the public, the first during the 1990s, others since then. Now and then a new one is added.