Château du Grand‑Blottereau

The estate sits within a park and is organized around a central main block (central living block) of two storeys beneath a high hipped slate roof. A formal 200‑metre avenue runs from the principal gate on Boulevard Auguste‑Péneau to the horseshoe entrance court, which is laid out with geometric French gardens and protected by moats along the north face. The ensemble stands on a raised granite base, giving the main house a deliberate, elevated siting in the western portion of the park.

Flanking the main block on both sides are open galleries composed of three arches that lead to pavilions set at right angles to the house. The plan is symmetrical: one end pavilion contains a chapel while the opposite pavilion houses kitchens and rooms for servants. To the west of the entrance court are the large service buildings, or communs, aligned with the courtyard and erected soon after the mid‑18th century transfer of ownership.

The walls are built of Chauvigny stone and tuffeau, traditional local building stones, set upon a granite plinth that lifts the structure clear of ground moisture. The north and south elevations mirror one another. Each approach has a double‑leaf entrance reached by a perron (stone stair): the north stair is square with three steps, the south stair is semi‑polygonal with seven steps and a stone ramp. Ground‑floor windows beside each door are capped at their keystones by carved faces called mascarons that depict human figures; the first‑floor windows above them carry mascarons with shell and lotus motifs.

The lateral elevations show minor asymmetries introduced in the original design and execution. On the west side one of four ground‑floor window openings is infilled, and several upper openings are likewise non‑functional. On the east, the ground‑floor windows remain regular while one opening on the first floor is filled in. These variations are visible in the masonry and window rhythm and reflect deliberate or later alterations to the external order.

Inside, the north door opens into a broad vestibule paved with grey marble. Two corridors run to either side and connect with the arcaded galleries. A suspended main staircase sits in the west corridor beneath a stone vault and rises to the principal floor. South of the entrance hall is a reception room that looks out to the gardens, flanked by two smaller chambers, forming the principal ground‑floor suite.

On the first floor the staircase delivers into the grand salon, which stands above the vestibule and the ground‑floor reception room. This salon is the only first‑floor apartment that faces both the entrance courtyard and the gardens, and three bedrooms occupy the other corners of the principal floor, one of them arranged around the stair in the northwest angle.

Ancillary structures and later additions remain part of the site fabric. The entrance grille at the front of the property and the boundary wall survive and are included in the protected elements. An icehouse known as La Glacière is present on the estate. A tropical greenhouse added in 1902 once stood in the grounds as part of the colonial garden project. A wartime blockhouse was constructed close to the main house during the occupation. Major exterior conservation from 1988 to 1993 repaired roofs, the north façades, the arcaded galleries and the side pavilions and made the building watertight; the interior has not been restored and the house remains closed for safety.