Wikimedia's map tool for Wiki Loves Monuments 2016. This tool doesn't have all eligible monuments, but many. A red label means that a monument still doesn't have any photos on Wikimedia Commons, while a green label means that there are photos. There is no requirement that photos depict monuments that don't yet have photos, so feel free to photograph any monument on the list.
Wikimedia's map tool for Wiki Loves Monuments 2016