Degree

There was a competition among the consorts of Vishnu namely 

1. Sridevi, 
2. Bhoodevi and 
3. Neeladevi on the degree of their devotion to Vishnu. 

Sridevi descended down to earth and repaired a sequestrated spot surrounded by paddy fields. She sat in devotion and influenced by her power of worship, all sages started worshipping her at the place. 

Realising that living alone would be improper, she engendered a theertha (water body) and propitiated Vishnu. Pleased by her devotion, Vishnu appeared at the spot. Bhudevi and Neeladevi followed her footsteps and acceded that Sridevi was the most devoted among them. Vishnu desired and stayed (thangal in Tamil) along with his consorts in the place. 

https://en.wikipedia.org/wiki/Ninra_Narayana_Perumal_temple
https://www.youtube.com/results?search_query=Ninra+Narayana

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Nava Tirupathi

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

Each of the nine temples represent one of the nine grahas of navagrahas

Although the number of temples are nine, it constitutes only eight divyadesams with two temples called Irratai tirupathi combinedly considered as just one divyadesam.

http://prtraveller.blogspot.com/2007/07/108-divya-desam-nava-tirupathi.html
http://www.tamilbrahmins.com/pilgrimage/2969-nava-thirupathi-tour-3.html

No	Temple	Perumal	Thayar	Distance from SriVaigundam	Temple Open Morning	Temple Open Evening
1	Srivaikundam Sun – Suriyan	Vaikundanathan Kallapiran	Vaikundanaayani Sooranathanayagi	-	8.00 – 12.00	5.00 – 8.00
2	Srivaragunamangai Natham Chandran	Vijayasanar Emmiderkadivan	Varagunamangai Varagunavalli	2 KM	9.00 – 12.00	1.00 – 6.00
3	Thiruppuliyangudi Puthan	Boomipaalagar Kaaichinaventhar	Nilamagal Pulingudivalli	3 KM	9.00 – 12.00	1.00 – 6.00
4	Erattai Thirupathi Raagu	Srinivasan Thevarpiran	Alamelumangai	10 KM	8.00 – 12.00	1.00 – 5.00
5	Erattai Thirupathi Keethu	Aravinason Chenthamarai Kannan	Karunthdankanni	10 KM	8.00 – 12.00	1.00 – 5.00
6	Thirukuzhanthai Perungulam Sani	Venkadavannan Maayakoothar	Kamalavathi Kulanthivalli	12 KM	8.00 – 12.00	5.00 – 8.00
7	Thenthiruperai Sukran	Maharenedun Kuzhaikaathar Niharilmukil vannan	Kuzhaikaathu valli Thiruperal Nachiyar	10 KM	8.00 – 12.00	5.00 – 8.00
8	Thirukkolloor Sevvai	Vaithananidhi Nichopavithan	Kumuthavalli Kollor Valli	8 KM	8.00 – 12.00	5.00 – 8.00
9	Azhwarthirunagari Viyazhan - Guru	Aadinathan Polinthunintrapiran	Aadinatha Nayagi	5 KM	8.00 – 12.00	5.00 – 8.00

Tube
https://www.youtube.com/results?search_query=Nava+Tirupathi