The south Indian temple cities such as Srirangam, Madurai etc, reveal the fact that the South-Indian concepts and norms of Vaasthu Purusha Mandala are ideologically a little different from that of the Vaasthu Purusha Mandala enunciated in the North Indian Architectural books.  The centre space where the main temple would be situated belongs to the formless brahma who has no beginning nor end.  In this region the prime temple would be built.  And, there would be fortifying walls built round it.  The place adjacent to this belong to the rest of the gods.  And the place even beyond that belong to the  human-beings.  The last portion belong to the evil-spirits and 'poothas'.

1.  Brahma's reign
2.  The region of the other gods
3.  The region assigned to human-beings
4. The region of the 'Poothas'.

If the North-Indian Vaasthu Purusha Mandala enunciates about creation, the South-Indian Vaasthu Purusha Mandala reveals the order  and regularity that prevail in the 'Created' universe.  This can be realized from the order and organization seen in the temple cities mentioned above The temple-city Madurai is a beautiful city with temple-towers.  It is aptly called 'Naan Maadak Koodal (The Communion of  four towers).   A renowned temple city it has in its fold temples such as the famous Madurai Meenakshiamman temple and Sundareswarar temple that have towers and fortifying walls and comprising of the 'thousand-foot' Mandap, the pond belonging to the temple and fortifying walls surrounding all these and entrance on all the four-sides of the walls and so built.  Nallur was not
just a temple city as like the city of Madurai.  It was also the capital city-Rajdhani.  That's why Nallur had qualities of a temple city as well as of a Rajdhani.

Here, it should be stated that there is a reason for my calling Madurai
as a temple-city.  In Madurai city the region where the temples are
situated is in itself constructed in the manner of a city only.  It is that
region or place that is referred to as the temple city of Madura.
Kanagasurya Singaiariyan who was defeated by Sabumala Kumaraya had spent his last days in Tamil Nadu with his sons Pararasasekaran and Segarasasekaran.
During that period the impact that the temple cities like Madurai had on
prince Pararasasekaran might have been the reason why when he expanded
Nallur Rajdhani he made it into a temple city.

VARIETIES OF ANCIENT INDIAN CITIES.

Thus, adhering to the rules of Vaasthu Purusha Mandala, cities of
numerous varieties had been built.  Thanthaga, Sarvadhopatra, Nandhiavartha,
Padmaga, Swaasthika, Prasthira, Kaamukaanda, Sadhurmuga ……. So they were called in various names. Of these, some varieties were best suited for small
cities or villages.  We can cite as example, the variety called 'Thanthaga'.
Such small cities or villages had two main gateways.  Those cities of the
'Nandhyavartha' variety had temple as their axis or central point.  Of those
varieties wherein there were two main roadways running North-South and
east -west which met in the centre and which had fortifying walls too,
swasthika was the very significant one.  This was the most popular of all
varieties.

Apart from these there were some more other varieties also.  Cities of
these varieties remained as each belonging to a particular caste only.  For
instance, we can name 'Kheta'.  In this type of city the 'suththiras' alone
were allowed to live.  As they were in the lowest strata of the caste-based
social system of Hindus they were considered as half-men, or, imperfect
human, so to say.  Hence, the cities which were constructed exclusively for
the class of people  were also built in an imperfect manner.  The structure
of such cities was such that there were no important or central place and
that the lay-out of these cities was such that lent less importance to the
city as well as to its structure.  The lay-out of these cities bringsforth
the sad state of being, of the soodras who lived in the insignificant layer
of the social strata.

The role that religion, caste and such other factors, played in the
architectural style and pattern of the city layout of the Hindus is being
revealed and highlighted even today by the informations that the books on
ancient hindus' architecture offer us.