concrete jungle

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic An urban or other populated area containing a high density of buildings constructed of concrete or similar materials, especially one which lacks greenery and which seems unattractive, harsh, or unsafe.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an area in a city with large modern buildings that is perceived as dangerous and unpleasant