Amsterdam lies in the Dutch province of Noord Holland on both banks of the Amstel River and the IJ-inlet. The city covers an area of 220 sq. km., of which only about 75% is land. The rest is composed of canals, waterways, and lakes. Much of Amsterdam lies below sea level; the city's urban area consists of 14 polders, which are areas of land that have been reclaimed from the swamps.

The city is built on a four-meter-thick layer of peat, with an underlying substratum of sand and clay to around 11 metres below N.A.P. (Amsterdam Ordnance Datum). Because of the soft unstable soil, all buildings are built on pilings made of tree trucks or concrete.

Canals

The necessity of reclaiming land for urban growth over the years has had a noticeable effect on the geography of Amsterdam. One of the city's best-known features is its canal system. Most of the canals were dug by hand, and each canal development marks a particular motive and moment in history:

The original canals in the Centrum (marked by "red light area" and "waterlooplein" on the map below) were among the earliest built, and intended to open up swampy land for city expansion beyond the medieval walled moat.

In 1613 a plan for the distinctive half-ring canal system was approved by the municipality. Large businesses and upper-class homes were built along the three main concentric canals (the Heren-, Keizers- and Prinsengrachts), while homes for the lower middle class were built along the smaller canals that traversed the three main ones.

The Jordaan area was used as gardens for city dwellers until it was developed as a working class neighborhood starting in 1640. Hazardous, noisy and smelly crafts and industries were not allowed inside the canal girdle, and housing prices were high within the canal ring, so crafts- and tradesmen moved their businesses and families into the neighboring Jordaan. The streets and canals follow the original garden paths and are quite narrow. Beyond the Singelgracht, which encircles the canal ring and the Jordaan, canals are less frequent