“Demolition” is a word with a priori negative connotations. But St Vitus Cathedral at Prague Castle would never have been built without first demolishing an older basilica on the same site, which itself had been erected in the place of an even older rotunda; Wallenstein Palace (Valdštejnský palác) in Malá Strana would not have been erected without first doing away with the small buildings and gardens that were there before it; the renaissance and baroque buildings of Old Prague would not have arisen without the drastic reconstruction or replacement of the older wooden and stone buildings that stood there. Demolition or, more commonly, aggressive redevelopment and the new structures that are then introduced have always formed two sides of the same coin. If today we admire the picturesque qualities of historic urban centres, what we are admiring is their vitality and their capacity for regeneration in response to constantly changing conditions.