For Realization, the contribution of the Gd is necessary.
This personal God differs from individuals to individuals, depending on their dispositions and their tendency towards a particular trait or emotion.
So you can worship God as Male, Female or an impersonal image, Linga.
It could be worshiped as one would a Child, Father, Mother,Friend, Love or even as a Foe!
Later came the Agamas, where collective worship was stressed(which is not in the Vedas).
The Agamas laid down Rules for Construction of Temples, sanctifying them with Mantras and the daily Rituals to be followed.
Some great Temples were built and they are in existence even today with Pooja being offered as laid sown by the Agamas.
Of the three principal Deities,Lord Shiava and Lord Vishnu have the maximum number of Temples.
Of these some are considered more Sacred than the others.
These Temples are called Punya Kshetras.
Legend lists 108 such temples for Lord Vishnu.
Though it said to be organised by the Azhwars,the savants of Vaishnavism,these places trace their origin to ancient times and are referred to in The Purans.
The Deities of the Temples have been praised and poems were composed on them.
These places of Pilgrimages are called the Divya Kshetras,
The First Divadesam is Sriranagam, the second being Srivilliputhur.
Being from Srivillputhur I would cal it as the first for Vishnu came in search of Andal while people seek him!
Read my post on Vishnu’s Navel, confirmed by Science.
The List of the Vaishnava Kshetras, based on Geographical Locations is provide below.
Detailed post on each of them follows.