Skip main navigation


In this section you will learn what fortified structures may look like on satellite imagery.

Fortifications are structures typically built for defence – but often secondarily as highly visual expressions of power. Examples of fortifications include castles, forts (or fortresses), and defensive walls and ditches. They are often large features and so are preserved in the landscape.

For more than 5000 years, defences have been built to protect communities and their resources against theft, attack, and warfare. We have seen examples of settlements with defensive walls around them. There are also examples of fortified buildings such as military garrisons, or castles and fortresses.

Below are two examples of fortified sites seen in satellite imagery.

Seen by satellite, Qahira castle sits on top of a steep hill, as shown by the shadow it casts onto the lower land around it. Several rings of vertical walls defend the site, and a sharply winding road with four hairpin turns leads up to it. On the innermost walls, small shadows at regular intervals reveal crenellations, while pools of water are visible in both the innermost and outermost layers of defence.
Figure 1: Qahira Castle, Yemen on Google Earth. Image © 2014 Maxar Technologies

 Seen by satellite, a rectangular compound has high walls on all sides and is accessible only by one narrow gate on each side.
Figure 2: Khan al Musalla, Iraq on Google Earth. Image © 2021 Maxar Technologies

What features stand out most clearly? How do fortified sites look different from unfortified sites? And what features do you think we should look for to help identify them with remote sensing? Tell us what you think in the Comments!
This article is from the free online

Endangered Archaeology: Using Remote Sensing to Protect Cultural Heritage

Created by
FutureLearn - Learning For Life

Our purpose is to transform access to education.

We offer a diverse selection of courses from leading universities and cultural institutions from around the world. These are delivered one step at a time, and are accessible on mobile, tablet and desktop, so you can fit learning around your life.

We believe learning should be an enjoyable, social experience, so our courses offer the opportunity to discuss what you’re learning with others as you go, helping you make fresh discoveries and form new ideas.
You can unlock new opportunities with unlimited access to hundreds of online short courses for a year by subscribing to our Unlimited package. Build your knowledge with top universities and organisations.

Learn more about how FutureLearn is transforming access to education