The Watchtowers In The Order Of The Golden Dawn

The Watchtowers are in represent the directions and are where the elements live or the four corners, with are north east south and west, and earth air, fire and water.. In the Order of the Golden Dawn a watchtower is though to be a spirit of one of the four cardinal points or "quarters" (north, east, south, and west). They are also associated with many traditions with each the four elements (earth, air, fire, and water) The Watchtowers are evoked during casting a circle.

also, "Watchtowers" may refer to the homes of the Guardians, with the guardians referred to as "Watchers" or "Guardians"

the four watch towers are set up to represent the outer barrier of your magical circle, to protect it and help establish a energy area
in which magick can be built. Each one of these elements is evoked and welcomed into the circle by the invocation, sometimes by name, and other times by a greeting

The watch towers are called upon to guard your circle and lean their power you your ritual or spell work, the power being that of the elements, with are what all life is created from.

" The following excerpt, from a book we recommend highly The Encyclopedia of Witches and Witchcraft1 explains briefly the difference between Elementals, Watchtowers, the elements, and the four quarters.
Please refer to this book for further information about the history of the elements. The elements are associated with the cardinal points of the magic circle and with a hierarchy of spirits- lower-level beings called elementals, who in turn are governed by higher beings, devas, also called the Lords of the Watchtowers, the Mighty Ones and the Guardians." So from that exerpt we see that the elements are Earth, Air, Fire and Water Elementals are said to be 'lower-level' beings, meaning very generally that they are not
God/desses.
Elementals are ruled over by higher beings, devas called by names such as the Lords of the Watchtowers, the Mighty Ones, and the Guardians." paganpath, Friday, http://paganpath.com/study/library/trads/167-watchtowers

I feel one should study and work on getting o know more about the elements and the watchtowers before trying to evoke them to your circle always, study first, and if you choose to call upon them always be respectful and do not for get to dismiss when you're done.
"Again, there is rarely a consensus on this topic in magickal circles. Generally, the circle is cast and invocations, evocations or convocations are utilized for the elements, Elementals, or Guardians. Usually the practitioner faces the corresponding direction (cardinal point) while invoking. These are some of the more popular invocations and convocations used by modern Witches" paganpath, Friday, http://paganpath.com/study/library/trads/167-watchtowers

In Wicca, these watch towers are the Guardians of the dimensional Planes. Each of the Watchers takes care of a "Watchtower" which is a one of the four quarters of the Ritual Circle.

In the Elder traditions of Wicca they belive they are ancient Gods known as the Old Ones who guard the portals to the Other
World.

in Many Wiccan books circle-castings no longer mention the Watchtowers. Another important matter is experimentation with the attribution of elements to the directions, instead of staying with the attributions used by the Golden Dawn and Gardnerian Wicca (north/earth, east/air, south/fire, west/water). Many Wiccans see themselves as participants in an earth-based religion; they believe their practices should reflect where they live and of the local environment. Both the Golden Dawn and early Wicca were active in Great Britain; traditional attributions derived from the British climate may not work for practitioners in other areas. An instance of this problem is Wiccans living in the southern hemisphere, who believe the north, not the south, as the direction most characterized by fire and heat. Some pagans choose to follow the practices of a historical pagan group or conform to local traditions; which may dictate a change of attributions

If find the watch towers and the elements they house to be very important to spell and ritual work, and I for one could not see not calling them, I'm sure as my studies advance on them my opinion might grown stronger or may even change, but for now I feel the aid and protection a crucial to spell and ritual work, as well as the power they at to it.