The Tuscan city of Colle Val D'Elsa in the province of Siena is not on many tourist excursions.

But this once flourishing medieval town along the Via Francigena pilgrim route is worth an extension as they say in trade.

Firstly, because the city is built on three gradients or hills and is formed of a borgo, castle and plain.

It looks like a Hollywood film set ready for a Saracen attack.

It was in fact founded right in the middle of the medieval era and was a major protagonist in the history of the free comunes and the struggle between the Guelfs and the Ghibellines.

Secondly, because Colle Val d'Elsa has preserved its reputation as a centre for the production of fine handmade crystal glass since 1331.

In the Museo del Cristallo or Crystal Museum you can admire examples from the golden period of the town around 1592.

The museum is unique in Italy and is located in the underground section of the former Boschi Glassworks.

The most important part of the tour shows the stages of glass production from 1820 when the first kiln was established.

The main difference between crystal and glass is in the presence of lead oxide, which alters the density of the glass.

Only glass containing 24% lead oxide can legally be called crystal.

Indeed, the refractive index of crystal approaches the optical properties of diamond.

The exhibiton of lead crystal glass and exhibition takes place every September. 

Master blowers give open air demonstrations of their craft and even today 95% of all the crystal glass made in Italy, and 14% of world production, still originates here.

www.cristallo.org