The ongoing renovation of ishigaki stone walls surrounding Nagoya Castle has gotten into full swing, with a 123-meter stretch of the 15-meter-high stone wall being removed so far.

In one of the country’s largest such renovation projects and the first at Nagoya Castle in 300 years, workers have so far discovered signatures engraved in the stones that identify lords who helped establish the fortifications.

Nagoya Castle, including the surrounding stone wall, is registered as a national special historic site. The stone wall was last restored around the end of the 17th century, according to a 1682 document.

The renovation project began in 2004, starting with repairs to the stone wall surrounding the entrance barrier at the Karamete-mon gate to Honmaru Palace, the main castle building.

The soil behind the stone wall, which absorbs rainwater, has swollen after many years, creating bulges. Without renovation, sections are in danger of collapse.

All of the wall’s 4,000 flat stones, or tsukiishi, used on the surface, as well as guri’ishi cobblestones used near drainage systems, will be removed and re-sorted before they are put back in place. Stones with cracks will be replaced and the structure will be leveled out.