Magnificence is when something is incredibly grand, beautiful, or impressive. You might describe the magnificence of a cruise ship, for example, with its elaborate ballrooms and large swimming pools.
When something makes a huge impression on you, especially for its hugeness or fanciness, it has the quality of magnificence. To a little kid, Disney World has magnificence, while an adult might be impressed by the magnificence of a first class European train car. In the fourteenth century, magnificence implied courage and nobility, as the word comes from the Latin root magnificus, which means both "great, noble, and eminent," and also "splendid, rich, or costly."