Regarded exceedingly sacred by the Parsi and Zoroastrian community, Udvada is a coastal town near the city of Surat in the district of Valsad. Udvava literally stands for `grazing ground of camels`, which was actually the town`s condition, prior to becoming a fishing village. It is renowned for the Zoroastrian Atash Behram fire temple.  This place of worship is the oldest still-functioning example of its kind, and is a pilgrimage center for Zoroastrians the world over.

The Udvada Atash Behram is one of nine Atash Behrams worldwide, eight of which are in western India (four in Mumbai, two in Surat, one in Navsari, and the one in Udvada), and one of which is in Yazd, in central Iran.

Ceremonial anniversary celebrations are held at the Atash Behram on the day of its founding. The ceremonies in Udvada are held on the ninth day of the ninth month in the Shahenshahi (imperial) version of the Zoroastrian calendar. Pilgrims from all over the world visit the temple on that day. Special ceremonies are also held on the 20th day of each month. In the Zoroastrian calendar, that day is dedicated to the divinity Verethragna (Avestan, Middle Persian Waharam, hence Behram), hypostasis of victory.

According to tradition and later as a result of legal verdict, nine priestly families of Sanjan and their heirs are the sole lawful guardians of the fire and its temple. They alone have the right to enjoy its income. The position of high priest passes in turn from the head of one family to the head of another.

Udvada also hosts a Zoroastrian heritage museum, sponsored by the Government of Gujarat.This museum contains summaries of the teachings and beliefs of lord Ahura Mazda, it has a large write up, that tells you about the history of the Parsi’s and Ahura Mazda. It also has explanations and write-ups on the holy ceremony of the Parsis called Navjote.

Preservation

The town, and its ambience, is under threat from the advancing sea (and consequent salinity) and commercialization. The Mumbai-based Save Udvada Committee, supported by the Indian and Gujarat state governments, is engaged in combating sea-driven erosion. There have also been attempts to get Udvada declared a World Heritage Site, to protect the ancient residences and the fire temple. The typical Parsi homes here with their high ceilings, sloped roofs with ornamental skirting, and double otlas (porches) are over a century old, and considered worth preserving.

Source:

https://en.wikipedia.org/wiki/Udvada

http://www.gujarattourism.com/destination/details/10/110

https://medium.com/@gocebe/the-history-and-geography-of-parsis-28b7b3d48e7f