How to search BY photo? (not photo search engine huh?)?

say i have a photo for eiffel tower for example and i want to know what is this? you know the difference? not google images huh? the case here that i have the image already i don't need another one .. i just need some informations related to it .. is that clear? .. another example i have a logo image and i want to know informations about it? .. i know that google make something like this but i lost its name .. i can't reach it .. can u help me?