Look at this:
http://sketchup.google.com/3dwarehouse/search?uq=07256339619360914543&scoring=m

The models of manhattan were available on Google 3D warehouse, but now they have been erased from the website.

Salut Stephan,

For me good textures are more useful than very-accurate shapes.

About the picture showing a city (N4a) : Is it the city of Pripryat as shown in the video game S.T.A.L.K.E.R ?

Oui, je crois savoir de quoi viens le problème : il suffit de vérifier chaque textures une par une en vérifiant les noms. Il faut aller dans materials, puis edit et là normalement le nom de la texture s'affiche. l'extension doit être .jpg et non .JPG ou .JPEG. En corrigeant cela le modèle devrait s'afficher correctement !

I don't know whether websites about textures in SketchUp exist or not, but I have a free texture for you below. I use it sometimes in some of my models. (Sorry for my english skills )

Hi,
Do you know GIMP? Gimp is a is a freely distributed piece of software for such tasks as photo retouching, image composition and image authoring. It works on many operating systems, in many languages.
You can create PNG files with this software.

Official site : http://www.gimp.org/