Although ...

The sentence beginning with the highlighted word is incomplete, giving the reader the impression that it is left hanging (Daily Telegraph, 29 August 2010).

This is because the entire sentence is a subordinate clause, and subordinate clauses ordinarily cannot stand alone and need to be attached to main clauses.  One obvious way to ‘rescue’ it is to end the previous sentence with a comma, and to tack the subordinate clause on at the end:

Demand is highest in Germany, Austria, Poland and central Europe, although the powerful light ... in historic homes.

Another solution is to change the subordinating conjunction although to the adverb however:

However, the powerful light ... in historic homes.