Vyuha

Vishnu is said to have manifested Himself in the Pancha-Vyuha forms—

1. Sankarshana in the east, 
2. Prad-yumna in the south, 
3. Aniruadha in the west, 
4. Samban alias Purushottama in the north, and 
5. Vasudeva in the centre. 

The sculptures of all these deities are found in the garbhagriha.

https://www.google.com/search?q=Nachiyar+Kovil

Eight Swayam-Vyakta Kshetras / Verse / Map

  

Srirangam Venkatadrischa SrimushNam Totaparvatam

Salagramam Pushkaramcha NaranarayaNAshramam

Naimisham Cheti ME SthananyasoU Mukthi PradhAnivai

YetusvashtAksharaIkAka: VarNamUrthir VasAmyaham

TishtAmi KrishNa KshEtrE puNya SapthakOgatha:

AshtAksharasya Mantrasya SarvAkshara Maya SadA

In this verse Lord Narayana points out that the eight

Swayam Vyakta Kshetrams of Srirangam, Tirupathi, SrimushNam,

Vanamamalai, Salagramam, Badri,and NaimisharaNyam,Pushkar

grant liberation to those who visit the place.

1. Srirangam Ranganathaswamy temple, 
2. Bhu Varaha Swamy temple, 
3. Vanamamalai Perumal temple and 
4. Tirumala Venkateswara Temple 

in South India 

and 

1. Saligrama, 
2. Naimisaranya, 
3. Pushkar and 
4. Badrinath Temple 

in North India.

https://thetirupathi.com/eight-swayambhu-temples-of-lord-vishnu-in-india/

http://www.shaktipeethas.org/vishnu-temples/topic67.html

The Lord as the Archa Murthy at each of these Kshetrams

signifies one Aksharam of his Ashtakshara Mantram

Om Namo Narayanaya.

 “om na-mo na-ra-ya-na-ya”

http://en.wikipedia.org/wiki/Narayana 

http://www.youtube.com/results?search_query=Om+Namo+Narayanaya 

Combo
https://ashtaksharakshetras.wordpress.com/
Neela Megha Perumal https://www.radha.name/news/general-news/astha-svayam-vyakta-kshetras