The four criteria for assessing class importance apply to chain towers as follows:
- Period (currency): Restricted. The tradition of building chain towers lasted for about 200 years, the first being completed in 1457 and the last being abandoned in 1678.
- Rarity: Very rare. Fourteen sites are known, with structures surviving on 5; although the sites of some unknown examples may be identified there is likely to be little remaining of such monuments.
- Diversity (form): High. The classification proposed above illustrates the diversity of this class of monument.
- Period (representativity): Medium. Chain towers were one of a wide range of similar classes of similar date; there are relatively few devoted to defence and this class is important in reflecting a change in defensive techniques.
Assigning scores to these criteria following the system set out in the Monument Evaluation Manual, chain towers yield a Class Importance Value of 33 out of a maximum possible score of 64, reflecting the rarity of this class of monument.