Referred to locally as "the Citadel" or "the Hill," the Halifax Citadel was originally known as Fort George. Situated atop Citadel Hill in Halifax, Nova Scotia, Canada, the Citadel is actually the fourth in a series of fortifications built to defend the port city. The centre of the massive, multilayered defensive works covering Halifax, the Citadel was not once attacked - possibly because of the obvious futility of such an action - and has served as a centerpiece to the city from its beginnings in the 1740s until the present day, where it exists as a reconstructed National Historic Site.

The "first citadel" was built in 1749 - the year Halifax itself was founded - as a rush job to defend against hostile natives. Not a single fortress, the initial construction was a half-circle of five square forts ringing the new settlement, linked together by a palisade of sharpened tree trunks. The forts themselves were squares with diamond-shaped tenalias at each corner allowing cover fire along the outer walls, the forts themselves placed at the outer edge of the larger wall for the same purpose. One of the five forts was built atop the large, 270-foot hill slightly inland from the settlement which eventually became the site of the three fortresses which followed.

During the American Revolution, the British authourities in Halifax realized the town defenses were woefully inadequate. A new, larger, more modern fortress was needed to defend against the possibility of attacks from the rebelling colonies. Four of the small forts were demolished, and a much larger, rectangular fortress was placed atop Citadel Hill. The new fortress consisted of an eight-sided blockhouse in its centre, large enough to house a hundred soldiers with cannon, with a large, open area surrounded by a low earthen wall. Completed in 1782, this fortress never saw action, although it served (like the following fortresses) as the site of the British garrison in the city.

A third fortress began construction amidst war clouds as the French Revolution began, with a growing risk of conflict between Britain and France which quickly turned into all-out war. An expansion of the 1782 fortress, the third attempt (finished in 1799) consisted mainly of a strengthening of the walls by replacing the low stone wall with a palisade and the beginnings of a masonry wall, as well as exchanging the blockhouse for a more permanent, well-equipped structure and adding more cannon positions - the 1799 Citadel had the facilities for between sixty and eighty cannon. The fortress also added a number of triangular redoubts which provided far more coverage for many of the gun batteries. This fortress was never attacked either, between the French fleet's obliteration at Trafalgar and the confinement of the land campaign in the War of 1812 to Ontario and Quebec.

A period of tension with the United States after the War of 1812, as well as Halifax's growing importance as a major port of the burgeoning British Empire, led to a final reconstruction of the Citadel. Begun in 1828 and lasting until 1856, the "final draft" of the fortress changed it in most ways. The end result was a masterpiece of military engineering. The large final fort was a masonry-and-earthwork structure which absorbed and expanded on the 1799 fortress, resulting in a twin-walled structure which gives the modern Citadel its distinctive star shape. A single narrow drawbridge allows access into the fortress, crossing a nine-meter-deep trench between the outer and inner walls. The outer walls and earthwork, which extend partway underground, are hollow, accessible only from the inner fortress through a handful of narrow passageways closed off by iron blast doors. There are no rifle ports or cannon positions on the outer wall facing out; instead, the outer wall's rifle positions face inward, allowing covering fire against any enemy troops who manage to pass over the first wall. The interior of the outer wall consists of a number of chambers with narrow entrances to each, creating the effect of a line of rooms roughly a third of a mile long - almost impregnable from the outside, and anything but easy pickings on the inside. The main fortress itself is a two-level structure entirely in stone, towering over the outer wall by a couple of meters, consisting mainly of the upper level's cannon and mortar positions - with provisions for perhaps a hundred guns overall. The outer edge of the earthwork-topped stone wall is a sharp, slick slope, almost impossible to climb over without falling back into the ditch. A large signal house on the upper level also permitted the Citadel to speak with the numerous forts around the city via semaphore and, later , telegraph. The lower level consists mostly of the things which keep the fortress running - stables, storehouses, workshops, a tremendous powder magazine storing some seventy tons of gunpowder, a large barracks in the interior parade ground, and even a school for the soldiers' wives.

Like the first three fortresses, the fourth and last Citadel never saw action - although it saw use through the Second World War. The Citadel was garrisoned by British troops until 1906, after which it served as a garrison for Canadian soldiers, a temporary camp for troops heading to and from Europe in both World Wars, and the centre of Halifax's air defense grid in WWII.

After the wars, it was closed down as a military installation, and was eventually declared a National Historic Site. Several years of renovation later, the Citadel stands in Halifax as it appears today.

The fortress is currently a major tourist attraction as well as a historical centerpiece to the city. Today, visitors may tour most of the fortress, with the exception of some areas which are not yet fully renovated, visit a military museum on the upper floor of the barracks complex, and watch rifle and artillery drills by the 78th Highlander Regiment. Halifax also marks the noon hour every day by firing a cannon from the Citadel's eastern face. On a more modern note, the Garrison Grounds on the western face of the hill, outside of the fortress, serve as a party field for major concerts in the city through most of the summer, most notably the major Canada Day festivities which happen on July 1 every year. As the Citadel once served as the defensive centre of the city, today it faces life as a living monument to those who built and served in it, a backdrop to far more modern affairs in the city, and - as a piece of the 19th century dropped into the centre of a 21st-century city - a symbol of the way things once were.

The Citadel did do its duty, protecting the city through its existence, one last time in December of 1917. When the Imo and Mont Blanc collided and exploded in what would be known as the Halifax Explosion, the Citadel and the hill it was on served as a shield for much of southern Halifax, diverting the blast wave from the huge explosion. Even today, travellers through the city can notice the houses and older buildings opposite the Narrows look visibly older than houses on the northern face of the hill - a reminder of the Citadel's first and last defense of the city.