This is the kind of project you normally develop for your thesis. It is much larger and more complex of what it can look at a first glance.
Googling around you will find a lot of BCS and master thesis on this topic. Read them and you will find almost all the information you need to develop your own system.
As a starting point you can use redpin: http://redpin.org/ .
While Google Maps can actually support indoor mapping and navigation, most likely it is not what you are looking for. If you want to use you own algorithm form routing, you cannot use Google Maps.
Have a look at the Open Source Routing Machine (OSRM): http://project-osrm.org/ .
