Timgad: how to read the orthogonal Roman plan

Useful to know

Timgad was founded as a Roman military colony by Trajan in 100 AD. UNESCO distinguishes its orthogonal device with the two main directions cardo and decumanus and the initial square enclosure. [1]

On the plan, first find these directions, then follow the smaller streets and public spaces. Thus, individual ruins receive a common framework. The regular network does not mean that every preserved building is of one moment or that the whole city has remained unchanged. Separate the original design from the subsequent development of the settlement.