The Current Digital Heightmap for the Netherlands (AHN) is a record of elevations above sea level for the whole country.
This is much used in archaeology as it as it helps to visualise both landscape and archaeological phenomena such as burial mounds, old river courses and depositions. Ground disturbance can also be detected.
The file exists in a number of versions and has been in use for some time. Standard viewers can be found on the internet but it is advisable for any visualisations to consult a specialist. By playing with shadow angles and use of colour fine nuances in the ground surface can be revealed. Archol's GIS specialists have a lot of experience with this and can offer their services to external parties.