Since the French Revolution, modifications and restorations have been carried out by successive owners, notably William Perry Dudley [fr] from 1922 to the late 1950s and the Atterton couple in the 2000s.

However, the ongoing collapse of the hillside is causing concern due to its potential impact on the stability of the promontory's edge and the houses constructed on the lower slopes.

The site is protected on two sides by the valleys of the Indre and the Gironde, which together form a small temporary tributary that also serves as the moat for the town's enclosure.

[N 1] At that time, large ancient constructions were generally considered the work of a powerful and prestigious civilization, that of the Romans, personified by its most famous representative.

[D 1] In 2002, fortification historian Nicolas Faucherre published a lengthy article in the Bulletin des amis du pays lochois, wherein he advanced novel hypotheses regarding the construction chronology of the entire castle site (keep and adjoining structures).

[13] According to a charter by Robert II the Pious, written between 996 and 1006, the builder of the structure in question could have been Fulk Nerra, who constructed a castellum on land belonging to the Abbey of Saint-Paul de Cormery without prior authorization.

[D 4] Subsequently, between 1020 and 1110, possibly at the instigation of Geoffrey Martel, the son of Fulk Nerra, who had recaptured the fortress from the counts of Blois, this keep was partially destroyed at varying heights according to its sides, then rebuilt with two additional floors, while its base was repaired and an outwork was added to its western face.

For instance, Cardinal Jean de la Balue, who was convicted of treason against the king, was detained at Montbazon for several months between his arrest on 23 May 1469, in Amboise and his transfer to Onzain in January or February 1470.

The debris from the structure was used as a landfill to reinforce the road to Spain (which later became the RN 10), while the Saint-Georges chapel, situated to the north, and a significant portion of the enclosure were also demolished.

[M 4] In December 1790, the castle walls were in a state of disrepair, posing a significant risk of collapse onto the rectory and other residential structures situated below on Rue des Moulins.

[3] Notwithstanding numerous cautions regarding the structural vulnerability of the building, a masonry vault was erected at the summit of the fourth level to buttress the pedestal supporting the statue.

The statue, which was hollow and constructed from riveted copper plates that had been partially filled with stones and concrete,[M 8] was eventually installed in 1866, which was the year of Joseph Delaville Le Roulx's death.

On 17 March 1922, William Perry Dudley [fr], an American architect and landscaper, purchased the castle site from Yvonne Dezarrois, the great-niece of Joseph Delaville Le Roulx,[V 2][N 2] for the sum of 9,000 francs.

[V 6] Additionally, he remodeled the site's access points, added crenellations to the towers, cleared the entrance to the underground passages, and completely redesigned the park, decorating it with statues commissioned by local sculptors or crafted by himself.

Additionally, he planted a few rows of vines, a practice documented as early as the nineteenth century, and developed a "Gothic garden" to the south of the master tower.

[V 7] His final project, completed in 1957, entailed consolidating the keep, which was at risk of collapsing due to the weight of the statue, through the construction of an internal concrete support system.

[V 1] In 1999, Harry and Jacqueline Atterton, an Anglo-French couple, purchased the property and initiated an ambitious restoration and enhancement program intending to open it to the public,[26] which they accomplished in 2003.

Since 2010, the site's promotion and activities have been managed by the "Black Falcon Knights" association,[28] which offers guided tours and workshops on a range of historical subjects, including blacksmithing, herbalism, ancient weaponry, and war machine demonstrations.

[29] The construction of the entire castle complex (main tower, forebuilding, and outer wall) employs a diverse array of materials, some of which can be traced to their original sources.

The two lower levels, which constitute the oldest part of the structure, are constructed with flint and lacustrine limestone rubble, with some sections exhibiting a herringbone pattern.

[35] The ground floor, which originally lacked windows—the openings in its eastern face appear to date to the late Middle Ages[D 11]—contains a wooden post partition that divides the level into two rooms lengthwise.

[37] In the 21st century, the thickness of the accumulated fill material within the ground floor area exceeds 6 meters,[38] leaving only the upper part of the load-bearing wall visible.

These include latrines built into the thickness of the eastern wall, their framing made of tuffeau, as is the case with all comparable features in the main tower at that time.

[D 14] The state of preservation of the upper level of the keep, which has been subjected to extensive damage and modification on multiple occasions—the tower has lost at least the top eight meters of its original height—notably during the addition of various structures to its summit (telegraph, statue, and its supporting vault, reinforced concrete belt), precludes the drawing of conclusions regarding its architectural style and function.

[D 15][39] It is postulated, on the basis of analogies with other edifices erected at the advent of the second millennium, that this floor may have constituted the domicile of the lord for his family or may have been allotted to the guards, two indispensable functions in a fortified manor house that have not been identified elsewhere in the main tower.

Access to the sole habitable room was via an external ladder, and the newcomers were compelled to engage in culinary activities within a wooden shed situated within the courtyard.

[V 1] This modest religious structure, dedicated to Saint George, dates back to the medieval period (12th century) and partially incorporates an older architectural foundation.

It appears that the castle chapel, constructed around the 14th century or slightly earlier, underwent a temporary change in function, serving as a metallurgy workshop instead of a religious facility.

However, its architectural plan, as evidenced by historical records, places it close to the former collegiate church of Notre Dame de Loches [fr].

Nevertheless, vestiges of the southern enclosure dating to the 13th century remain, situated adjacent to the avant-corps and the northwest corner of the main tower, as well as to the west of the access ramp.