I was wondering about those giant, closely spaced industrial-looking buildings on the outskirts of town. Apparently greenhouses: http://goo.gl/maps/qIQxk

Yes, those are greenhouses. Move north-east for a bit, and you hit the Westland (http://en.wikipedia.org/wiki/Westland_(region),_Netherlands), an area of greenhouses with the occasional road or house in-between.

At night, from the ground: http://straatkaart.nl/2286JK-Albert-Schweitzerlaan/media_fot...

At night, from space: http://www.flickr.com/photos/astro_andre/6769497883/in/set-7... (the large bright spot are greenhouses with artificial lighting to speed up plant growth)