Externally, towers and spires are characteristic of Gothic churches both great and small, the number and positioning being one of the greatest variables in Gothic architecture. In Italy, the tower, if present, is almost always detached from the building, as at Florence Cathedral, and is often from an earlier structure. In France and Spain, two towers on the front is the norm. In England, Germany and Scandinavia this is often the arrangement, but an English cathedral may also be surmounted by an enormous tower at the crossing. Smaller churches usually have just one tower, but this may also be the case at larger buildings, such as Salisbury Cathedral or Ulm Minster, which has the tallest spire in the world, slightly exceeding that of Lincoln Cathedral, the tallest which was actually completed during the medieval period, at 160 metres (520 ft).