Most of the Hindu temples ancient, medieval and contemporary, and even cities, forts, castles and private houses have the image of Ganapati on the lintels of their main entrances, as Ganapati is believed to keep calamities, detriments and evil away. The Ganesh-pol, gate, at the Amer fort in Jaipur, Rajasthan is globally known for its great magnificence and unique artistic quality and that at Gwalior fort for its massive structure. In Indian ritual practices, Ganapati is invoked before a rite is begun so that it is performed detriment free. Lord Vishnu has himself prescribed the Adi-puja, first worship of Ganesh Ado pujya Vinayaka. Hence, before a devotee enters the temple and offers his services to the presiding deity, he is required to first make offerings to Lord Ganesh. His lintel image accomplishes this object.
Inside the entrance, which in the prescribed temple architecture should be the temple's ardha-mandapa, portico, devotee encounters the auspicious bell suspending from its ceiling. He rings it before entering the sanctum sanctorum, as the sacred sound of the auspicious bell, reverberating with the power of mantras, re-enlivens the deity and the shrine. In Indian tradition, before a deity is installed in the sanctum sanctorum, life is instilled into its image, which is its Prana-pratishtha. But, despite, a devotee is required to re-enliven the deity for himself and for doing so he rings the bell and through its magnetism sound, sends his life-current into the image. It is only after such common magnetic circuit is created between the deity and devotee that the deity responds to what the devotee desires. To a common devotee, the bell the power of mantra condensed, is, thus, the auspicious instrument that connects his intrinsic being with the deity, the same as yoga and dhyana are a yogi's instruments. The artefact is thus dually sacred, as it combines mantra the condensed cosmic nada, sound, contained in the bell with the most auspicious deity of Indian pantheon. If hung over the entrance of the abode, either of god or man, this Ganapati-bell will be both Ganesh on the lintel of the entrance as also the auspicious bell in the portico. The artefact is a divine chandelier, which does not spread the light that one lights with one's own hands but the unseen light that emits from it the divine magnetic rays.
This description by Prof. P.C. Jain and Dr Daljeet. Prof. Jain specializes on the aesthetics of ancient Indian literature. Dr Daljeet is the chief curator of the Visual Arts Gallery at the National Museum of India, New Delhi. They have both collaborated on numerous books on Indian art and culture.