The Bastille is the name of a fortress culminating at 476 m (ft) above sea level, located at the south end of the Chartreuse mountain range and overlooking the city of Grenoble, France. The Bastille, which also gives its name to the hill, is the main tourist site of the Grenoble area, with 600,000 visitors per year.

Geography 
The fortress lies on the final promontory of Mount Rachais, a narrow mountain that is the most southerly of the Chartreuse range.

The plateau of the fortress' main fortifications is situated 264 metres above a singularly flat valley floor which is glacial in origin. The melting of the Isère glacier approximately  years ago led to the formation of a vast lake stretching from Voiron to Albertville and which remained for approximately  years. The filling-in of this lake by alluvial deposits created the perfectly flat valley floors that are in evidence today.

The location of the fort was chosen because it facilitated the surveillance and control of the city of Grenoble, from the 19th century onward, as well as the valleys of the Isère and the Drac, all the while being difficult to attack and overthrow because of the cliffs and steep ground by which it is surrounded.

History
Requests to fortify this hill had been made by Francis I in 1538, and by Charles IX in 1566, but these were not acted upon.

The Lesdiguières Era

In December 1590, Lesdiguières, head of the Huguenots in the Dauphiné, took control of the city of Grenoble which had been until then under Roman Catholic control. This took place during the eighth and last Wars of Religion. With an army of  men gathered at Moirans, he marched towards Grenoble, passing through Saint-Martin-le-Vinoux and then over a spur of Mount Rachais called the Rabot, there avoiding a fortified stronghold.  There was a single canon positioned on the slopes of Mount Rachais because this rocky spur was thought to be enough of a natural barrier to deter the advance of hostile forces. But in spite of a permanent state of alert and 24 watch points in the city, Grenoble fell to Lesdiguières after more than three weeks under siege.

In 1591, having become governor of Grenoble, Lesdiguières immediately ordered the construction of two new defensive elements for the city. First, a small fortified citadel around the Tour de l'Isle (a square tower built on the banks of the Isère, which today stands next to the Museum of Grenoble) so as to have a safe place to withdraw to in case the city was attacked.  Second, a fortress on the summit of the hill so that no enemy could approach the city from the Chartreuse without being challenged. This fortress, or bastille, which would give its name to the hill, was completed the following year in 1592. Comprising a tower and a series of small bastions, and with a building to lodge the troops, it was encircled by a wall approximately 1.3 metres thick around an area 68 metres long and 50 metres wide.

At the same time as these works were taking place, the Roman city wall, 13 centuries old and ill adapted to withstand the artillery of the time, was removed. New defensive walls were built, equipped with six bastions and two half-bastions capable of resisting artillery assault. The works encompassed the suburbs that had grown up around the original Roman city walls, thereby increasing the surface area of the city by, and were finished by December 1606.

In the first few years Lesdiguières used the Piedmont architect Ercole Negro, then later, from 1611, the royal engineer Jean de Beins. In 1611, after a pause in the works, construction began on the fortifications descending from either side of the Bastille towards two new monumental gates situated at points on the banks of the Isère approximately 1 km apart.

The Porte Saint Laurent upstream on the Savoy side of Grenoble was finished in 1615, and the Porte de France downstream was finished in 1620. For the first time, a road cut in the rocks along the banks of the Isère meant that it was no longer necessary to cross the rocky spur by the Montée de Chalemont to get from one gate to the other. These monumental gates still exist today, but as for the fortifications there remain only the vestiges of three bartizans and a staircase in the form of a tower in the Jardin des Dauphins. These works on the two branches of fortifications were completed in July 1619.

The Vauban Era

A century after the construction of the Bastille, the military architect Vauban, during his first inspection of the fortifications of the Alps in September 1692, alerted the king, Louis XIV, to the weaknesses of the defences of Grenoble. In his report, he described them as "weak, unfinished, poorly maintained, especially those of the Bastille", which he said were "badly cut, or rather a closed bauble, but without rhyme or reason, occupied by a vintner who is the governor, or at least who has the keys, with twelve cows, eight goats, a mare and a donkey for the whole garrison!".

However, his program of improvements to the fortifications of the Bastille would be ignored, as was his project for the enlargement of the city walls to the south that he proposed during a second visit in July 1700. Only a few terraces and two powder magazines were built. 

During the 18th century, the absence of any threat from the frontier of the Alps led to the lack of interest in any more military projects for Grenoble and the fortifications were no longer maintained.

In addition, due to the extensive flooding of the Isere in September 1733, and December 1741, what monopolized the minds of the authorities were what to implement to overcome these disasters' possible occurrence in the future. Many projects developed by engineers and surveyors between 1741, and 1787, were plans to divert waters of the river south of the city. But due to lack of resources, these projects remained for the approval by the board of Bridges and Roads; they were permanently abandoned in 1790.

The Haxo Era

After the rout of Napoleon in Europe, the treaty of Fontainebleau in 1814, and that of  Paris the following year put Grenoble back on the frontier opposite the Kingdom of Sardinia. Louis XVIII therefore decided in 1815 to reinforce his military presence on the borders. The following year, he charged General Haxo with the task of improving the fortifications of Grenoble that had become outdated and dilapidated.

After several rough drafts of the plans of the fortress, and much to-ing and fro-ing between Grenoble and the Fortifications Committee in Paris from 1822 to August 1823, the definitive plans for the fort of the Bastille that we can visit today were finally adopted by the committee in its meeting of 29 August 1823.  The first works on the site of the new fortress and its new fortifications began on 16 April 1824. The chief of the battalion of Engineers on site was Commander Tournadre.

On the slopes which alternated between rocky points, cliffs and scree, the use of contour maps allowed the precise calculation of position and height. The quarries of the Porte de France below supplied most of the stones which were transported up the hill by mule.

On the western side of the hill above the Porte de France, General Haxo followed the line of the 17th-century, walls and turned them into much larger walls flanked by casemates and bastions. At the top was the keep, or the fort, rebuilt after the demolition of the Bastille of Lesdiguières. Preceded by a moat, the fort is a rectilinear building composed of three floors of casemates in dressed stone, built between 1825, and 1830. Immediately adjacent to it, a barracks was built between 1827, and 1838 to lodge 100 men, officers and NCOs. A century later this building became a restaurant. In 1836, a powder magazine was built below the barracks. In spite of the roof having caved in, it is still visible today from the Vauban Viewpoint (the restaurant terrace).

Still on the western flank, lower down, there is the more modest fort of the Rabot with its citadel, situated within the defensive walls. Built between 1840, and 1847, close to the old Rabot stronghold of the 15th century, some fifty metres above the city, its role was to lodge up to 900 troops and their officers together with their artillery and a powder magazine far from the likely battlefront. Access is controlled by a monumental gate with a drawbridge. Since 1970, this fort has belonged to Grenoble's university and is used as student residences.

On the eastern flank, the Porte Saint Laurent side of the hill, General Haxo decided on a much more direct route for the walls than the line used by Lesdiguières. Rising above the Porte Saint Laurent are some five terraces of casemates. Then comes the first shorter section of wall linking the Porte Saint Laurent with two floors of mid-level casemates, and a second longer section of wall leads directly from there to the lower casemates of the Bastille. Running alongside each of these two walls is a staircase, with some 80