A restoration is when you bring something back to what it was. A crumbling house that is lovingly-rebuilt in its original style, a king who was kicked off his throne only to get it back — these are restorations.
Notice the difference between renovation and restoration. If you restore a 1950s house, you use period materials and effects. A renovation might include new things. Restoration always means a putting back: if you've been ill, but get better, you might talk about your restoration of health.