Sriranga Vimanam

The Vimana is verily the external Paramapada itself. The Vimana is in the form of the Pranava (the life sustaining mantra). The four towers are marvelously akin to the four Vedas and the Lord, Sri Rangasayee is expounding the import of the Pranava.

Srirangam, the premier Vaishnava temple in South India is the first and foremost among the 108 Vaishnava divyadesas. All the Alvars have sung in praise of the deity enshrined in the huge temple in the center of the town. The Sri Vaishnava Acharyas from Nathamuni are found to have taken an active and abiding interest in the management of the temple.

Reference: A Brief History of the Srirangam Temple