Ardleigh stands on a flat gravel plain in open countryside between Colchester and Manningtree. The parish measures some 6 kilometres east to west and about 5.5 kilometres north to south. It consists principally of agricultural land, but there is an obvious village centre, in the vicinity of St Mary's Church and the A137/B1029 crossroads.
To the west and south of the village centre, there is a valley system, which may no longer be very apparent to the casual passer-by. Ardleigh reservoir fills a large part of one of these valleys and the only obvious sign of that valley's existence is at John de Bois Hill. However, there is also a hilly, sunken lane leading down into the wooded area of Spring Valley, which is strikingly different in atmosphere from the essentially flat gravel plain on which most of Ardleigh lies.
Early maps show the village concentrated at the crossroads with the church just north-east and most other buildings lying to the west, along the road towards Colchester. This remained the case until well into the 20th century, despite the development of the railway line and associated buildings to the south of the village.
There has been considerable expansion of the village centre since the end of World War II, most notably in the form of:
The parish of Ardleigh comprises in addition to the village centre, a number of hamlets, each with its own character:
In addition to these readily identifiable hamlets, there are individual dwellings along most of the narrow lanes that run through the farm land surrounding the centre of Ardleigh.