Urban Archaeology: The City Beneath Your Feet

The branch of archaeological science called Urban Archaeology is concerned with the study of cities. Cities first arose about 5,000 years ago in Mesopotamia. Archaeologists define a city by population size and the existence of centralized political structure, craft specialists, complex economies, and social stratification.

Urban Archaeology is a sub discipline of archaeology specializing in the material past of where long-term human habitation has often left a rich record of the past. Archaeological  excavation within historic cities therefore often produces a thick stratigraphy dating back to the original foundation and telling the story of its history.

Urban Archaeology has special problems not seen in other forms of archaeology, particularly in those cities with long occupation histories. Landfills, reuse, and rebuilding have created massive amounts of artifacts and extremely complex stratigraphic levels.  Urban archaeologist attempt to record their field data accurately, preserve any artifacts and hopefully answer some questions about the development and history of the city they are studying.

The dense stratigraphy of cities pose problems for the archaeologists who first excavated them. Space for excavation is usually limited to the size of the open plot and one layer of archaeology needs to be excavated before the next one can be exposed. This involves the method of "single context recording." Here the archaeologist is involved in  drawing each feature individually in plan and then relating its position to the site grid rather than planning large areas at once. Each drawing is made on a square piece of translucent film representing a 25 square meter grid square.
 
The site is excavated down to the first significant layer of archaeology and features excavated and recorded as normal but also planned as single contexts. The site is then reduced to the next layer of archaeology and the process begins again. The excavation and recording can continue until natural deposits are reached. A small, deep trench known as a “sondage” is often excavated at first to provide a view of the entire stratigraphy at once and give an indication of the quantity of material to be excavated.

Once the work is finished, the square sheets can be overlaid onto one another to provide a picture of the site. By identifying which features cut others and using information from artifacts and ecofacts an archaeologist can isolate various phases of activity and show how the use of the site developed of periods of hundreds or even thousands of years.

Methods to cope with urban complexity include sampling strategies, heavy equipment to remove overburden, and the Harris Matrix to track archaeological components.

The first urban archaeology project was probably at Pompeii during the 18th century.