Custom Maps created by Marko Teittinen [This app currently has 99 Five Stars out of 138 reviews]
Use almost any map image as offline GPS map.
Custom Maps makes it easy to create GPS maps from map images, and those maps can be used anywhere, even when you have no data signal for your Android device (it works on both phones and tablets).
Custom Maps can use photos of paper maps or brochures, and pictures of maps posted at trailheads or at the entrances to amusement parks. It can also use .jpeg or .png images downloaded from the internet and screenshots of PDF maps.
All you have to do is choose two (or more) matching points that are
common to both the map image and Google Maps, and Custom Maps can then
show your GPS location on the map.
As the map images are stored on the phone, Custom Maps works offline without data signal. This is useful if you go hiking in national or state parks, and it can help you avoid international roaming charges abroad.