There were many factors that went into determining the city layout style and pattern of the Hindus.  The Nature and structure of the land, the Nature & structure of its soil, the social system prevailant in the land as like the caste constraints and restrictions etc, scriptures all played an important role in the city lay-out style and pattern of the Hindus. According to the structure and quality of the land they had divided it into three categories.

Jangala:
This referred to the dry land with no water, river and other resources.

Anopa:
This refers to the highly fertile land with abundant water resources
and  cool, pleasant climate.

Sadhana:
The average kind of land that was neither Jangala nor Anopa was called
thus.

The role played by the colour of the soil, its dour, the sounds
Produced by it, its flavour in the city layout pattern of the Hindus, has
been well brought out by the western author Andras Volwahsen in his work
called 'Living Architecture - Indian', of which some lines are given below:

'' The colour of the soil, its sound, flavour, the feeling it produced were all taken into consideration and studied with great care.  The colour of the sand identified the castes of people who were suitable to be settled there.  White, red, yellow, black were important colours.  The white colour soil was considered suitable for brahmins, the red for kshathrias, yellow for Vaishyas and black colour soil for soodhras.  There also existed
connection between the flavour of the soil and the caste system.  The sweet soil was considered to belong to the brahmins, the hot and pungent soil to the Vaishyas, the soil with bitter flavour to the 'soodhras'.  The soil which when tapped would produce sounds like the bark of dogs or the bray of donkeys or thehowl of the jackal should be avoided at all cost.''   (Living  Architecture Indian - page 44)

The slant or declivity of the land structure was also taken into
account.  The city should be built on the soil that has declivity towards
the northern or eastern side.  The hindus believed that the south bound
declivity would bring death and the south west bound slope, sufferings;
west-bound slope-poverty and destruction of crops; declivity towards the
north west direction-war. After the land most suited for constructing the
city was chosen in this way, from out of the 32 different varieties of
'Vaasthu Purusha Mandala' the suitable variety would be selected by a guru
having great scholarship in astrology.  The city would be constructed in
square shape (if it proves impossible, in a rectangular shape).  Andreas
Volwashsen says in his 'Living Architecture Indian' (page 47) that from the
informations given in the 'ancient books ('suvadikal')  on varieties of
architectural styles and patterns we come to know that the cities of perfect
square - shapes belonged to the brahmins alone, and, as for the other castes
they should live in rectangular - shaped cities only.  And, the layout of
the city which would be constructed thus with the right and suitable Vaasthu
Purusha Mandala chosen would appear as follows:

1. Fortitying walls would be built round the city.

2. The city would appear as a big square comprising of so many small  squares, separated by the roads, that run north-south and east-west.

3. The city would have been divided into two parts by two broad royal   roads that run north-south and east-west.

4. The royal roadway thus built would differ according to the character of  the city.  Forn instance, in the case of big cities this royal roadway would  be 12 metre width and in ordinary cities it would be of 10 metre breadth and if it is a city with just the market place, it would be of 8 metre width only.

5. To go round the city, on the interior side o the fortifying wall also a road would be built.  This road would be as wide as the royal roadway. Apart  from this the ancient hindus’ books on Architecture also speak of what sort of people would live in which direction of the city.  We can cite the   following as examples to this:

a, 'The habitats of such people as brahmins, astrologers, the royal  authorities and officers of royalty and police force should be in the  North and North west regions.

b, The dwelling places of goldsmiths and those who do such other  works should be in the southeast reion.

c, The dwelling places of prison authorities, soldiers, fishermen and cowherds should be in the southwest.

d, Market place in Northeast.

e, Places like the royal palaces should be in the east-  So, the ancient hindus, books on Architecture say.  Though these rules and   regulations could not be fully adhered to while constructing a city,  the dwelling places situated in the city should certainly be built with castewise divisions.  All these tell us in clear terms the role that caste   played in the field of city layout.