Bourgogne-Franche-Comté · Yonne, France

Guédelon

The castle being built from scratch, right now, with 13th-century tools and techniques: begun in 1997 in a former quarry, Guédelon is the world's largest experimental-archaeology site, where quarriers, masons, carpenters and rope-makers raise a Philip-Augustus-style castle before your eyes. Restorers of real châteaux come here to learn how it was actually done.

At a glance

Built: Begun 1997 — still rising
Style: 13th-century castle, built today
Commissioned by: Experimental archaeology project (Michel Guyot & Maryline Martin)
Signature feature: A genuine medieval building site, alive and working
The rules: Period tools, materials and methods only — everything made on site
The knowledge: Findings feed real restorations, including Notre-Dame's carpentry
Time scale: A quarter-century in, and gloriously unfinished
Visiting: Open to visitors (seasonal calendar)