The city London is the Capital of Great Britain. It developed on both sides of river Thames, which is the most impartant river of Britain. Originally it was of great importance for trade, because goods from the sea, goods transported down the river and goods on the roads crossing the river all met here. As always around rivers the underground is covered by loose, water-filled sediments, deposited by the river. This geology is not suitble for caves. But like any other big city on earth it has a great number of artificial structures which were dug in the centuries for various reasons. The three main reasons for underground structures are obvious, vaults, cave tombs or crypts, and infrastructure like subway or sewers. In other words, riches, life and death. And there is a fourth important reason: shelters as a result of World War II.

The sites at London are quite impressive, and due to the high number of inhabitants and tourists very well developed and visited. Most sites are not accessible to tourists. Others are not listed because they are only accessible on very rare events, like the closed London Underground stations. In such cases its necessary to check the respective website and book well in advance. That's unfortunately impossible for tourists, so these sites are factually only for locals. The number of such hard to visit sites is enormous, and there is actually a Wikipedia page for this topic which we linked below.