Take a look at more than 35 sketches by Urban Sketchers around the world that you can choose from in the Flickr set here if you make a donation . For a small donation, you can download high-resolution image that you can print out and display. If you make a donation of $75 or more, you can choose a print from this set, sent to you directly from the artist. More on how to donate is in this post on the Urban Sketchers blog.
The money that you help raise will go toward organizing an international symposium and cover a scholarship program to encourage artists to sketch and their part of the world, one drawing at a time. Thank you for your interest!