London

But at dawn the happiness and the rumours died away. The lights in the north belonged to a huge city all right, but it was not crippled; it was heading south at top speed, and it had a hungry look. The Guild of Navigators soon identified it as Panzerstadt-Bayreuth, a conurbation formed by the coupling together of four huge Traktionstadts, but nobody else cared very much what it was called; they just wanted to get away from it.

Chapter 18: Bevis, Mortal Engines, pg 74/152