I like the use of concrete in the Charles de Gaulle airport in Paris.
I just got back from a ten-day study trip to Barcelona, Spain, and have almost 2,000 photos to process. Here's the first one I'll post.
Camera: Nikon D5200
Lens: AF-S DX Nikkor 18-55mm f/3.5-5.6G VR II
Shutter Speed: 1/40s
Aperture: f/4
ISO: 200
Focal Length: 25mm