Queen Elizabeth II still has a few years to go to be the longest reigning monarch in the United Kingdom. Queen Victoria lasted almost 64 years during a period of time that is now known to be the Victorian era.
That era represented the height of the Industrial Revolution, a very significant period of progress in the United Kingdom for everything social, economic and technological. The British Empire expanded greatly under Victoria's reign, becoming the strongest global power of the time.
Queen Victoria was almost entirely of German descent and arranged many marriages across the continent, thus tying Europe together, earning the nickname of "Grandmother of Europe".