why so many temples

We all have been taught that God is one, but yet we keep seeing so many temples of various God and Goddesses around. I go back to the knowledge that I attained in childhood and recall the importance of three Godly characters I have kept watching on tv. Brahma Vishnu and Mahesh and then their different avtars. In the city of temples in Ujjain I stand confused seeing so many temples with similar looking idols and Shiv Ling in various temples by different names. Like always I ask myself for an answer and my limited mind gives me an answer which was as follows- like any organisation has a head and various employees of that organisation are assigned duties, God is one and his organisation is based on simple principle of faith and love. Various forms that we know off and the million names I don't know of are his employees who have designated task to fulfill and are to be approached as per our desire. For e.g. Laxmi Mata is to be approached for wealth, Maa Saraswati for knowledge and so on. I am not certain that I have come to right conclusion but this is what I could discover. I might be wrong but that's ok till I find a better answer. Manisha Dawar