With just a plain paper sketchbook and a ballpoint pen he sketched his impresssions of the city as he experienced it. He has collected these experiences on his blog in a category "News from Warsaw."
If you go to his main blog address you'll find other work as well: Richara Câmara on blogspot .
I encourage you to check out and be inspired by his work. He captures a wonderful sense of space and depth with just a few simple lines.