Granada has its usual quotient of churches, museums etc. typical for a southern European city. However, Granada has the Alhambra which is considered by some to be one of the 10 wonders of the world. In case you don't know, the Alhambra is a massive castle constructed over many centuries.
It consists of gardens, fortifications and sumptuous palaces. It was the home of many of the Arab Sultans who ruled the whole province so I suppose for centuries it received the optimum in interior decoration and architecture.
If you read the Koran, it continually repeats the idea that heaven is a garden with running water. From this perspective you could say that the Alhambra is an Arabic attempt to create heaven on earth. Nowadays, two million people visit the palaces each year and 8,500 people visit the Alhambra every day. It is therefore Spain's most visited monument. Even the biggest philistine would be impressed.