This museum is indeed unique: it is missing. Apparently, no one knows where it is. In an attempt to find it, a website about fire hydrants (http://www.firehydrant.org) pleas, "We do not know where this outdoor fire hydrant museum is and of course are quite anxious to find out. If you have even seen this place or know where it might be, please send us an email and let us know."
Click here to see a picture of the museum. There are 24 hydrants in the picture, including a two Ludlow Valve hydrants, one Glamorgan hydrant and two Corey hydrants. There are no dogs in this picture.