The case study presented is a prime example of integrated geophysical-archaeological prospection. The aerial photographs available are complemented by non-destructive geomagnetic and geoelectric surveys with a reading distance of 0.5 m or less. To gain depth information and provide higher resolution, ground-penetrating radar (GPR) data are integrated. The GPR data were collected in a 0.5 ð 0.05 m raster and visualized as black-and-white time or depth slices. The developments presented allow us to incorporate GPR into the standardized interpretation process of archaeological prospection based on a geographical information system (Grs). Using GPR and all the other prospection data available as a basis, a detailed three-dimensional interpretation model of the monument detected, the southern part of the forum of the civil town of Roman Carnuntum, is created.

The Swedish UNESCOWorld Cultural Heritage site ofthe Birka and HovgÔrden Iron Age settlementsiswellsuitedfor the testing of high-resolution archaeologicalprospection methods.In May 2006 ground-penetratingradar (GPR) and magnetometer test measurementswere conducted at Birka, resultingin data ofoutstanding qualityand new archaeological discoveries, but also demonstrating the need for increased spatial sampling regarding GPR prospection at complex Scandinavian sites. Therefore Birka was selected as a testing ground for a pilot study investigating the suitability of thenovelmultichannel GPRarray system MIRA (MAL-Imaging Radar Array) forefficient, large-scale GPR surveyswith very dense spatial sampling. The study was conducted in May 2008 by MAL-Geoscience AB in collaboration with the archaeological prospection unit of the Swedish National Heritage Board. The very high-resolution three-dimensional GPR pilot survey demonstrated that it is possible to survey 1ha and more per day with 8 cm cross-line spacing, mapping archaeological structures in unprecedented resolution, such as postholes of only 25 cm diameter.This paper describes the tested technology and methodology as well as the fieldwork and the results of the study.

Traditionally, ground‐penetrating radar (GPR) measurements for near‐surface geophysical archaeological prospection are conducted with single‐channel systems using GPR antennae mounted in a cart similar to a pushchair, or towed like a sledge behind the operator. The spatial data sampling of such GPR devices for the non‐invasive detection and investigation of buried cultural heritage was, with very few exceptions, at best 25 cm in cross‐line direction of the measurement. With two or three persons participating in the fieldwork, coverage rates between a quarter hectare and half a hectare per day are common, while frequently considerably smaller survey areas at often coarse measurement spacing have been reported. Over the past years, the advent of novel multi‐channel GPR antenna array systems has permitted an enormous increase in survey efficiency and spatial sampling resolution. Using GPR antenna arrays with up to 16 channels operating in parallel, in combination with automatic positioning solutions based on real‐time kinematic global navigation satellite systems or robotic total‐stations, it has become possible to map several hectares per day with as little as 8 cm cross‐line and 4 cm in‐line GPR trace spacing. While this dramatic increase in coverage rate has a positive effect on the reduction of costs of GPR surveys, and thus its more widespread use in archaeology, the increased spatial sampling for the first time allows for the high‐resolution imaging of relatively small archaeological structures, such as for example 25 cm wide post‐holes of Iron Age buildings or the brick pillars of Roman floor heating systems, permitting much improved archaeological interpretations of the collected data. We present the state‐of‐the‐art in large‐scale high‐resolution archaeological GPR prospection, covering hardware and software technology and fieldwork methodology as well as the closely related issues of processing and interpretation of the huge data sets. Application examples from selected European archaeological sites illustrate the progress made.

Over the centuries many archaeologists have investigated the site of Stonehenge and we now know a great deal about the phasing and nature of the site. However, the area around the henge, while containing many symbolic and ritual elements, is curiously ‘blank’. The Stonehenge Hidden Landscapes Project aims to place the site and its development through time within a landscape context using fast and accurate ground‐based geophysical techniques. The project has developed a rapid strategy to map, visualize and interpret landscape‐scale data and is applying the strategy to the area known as the Stonehenge ‘envelope’. The data are interpreted within a data rich three‐dimensional data cube that has provided new insights regarding the apparent blank areas surrounding Stonehenge. It is an aim of the project to discover more about Stonehenge by looking out from the site rather than looking at it. Copyright © 2012 John Wiley & Sons, Ltd.