Successive Golden Rectangles dividing a Golden Rectangle into squares (The Alhambra).

The Golden Rectangle and the Alhambra

A golden rectangle is a rectangle whose side lengths are in the golden ratio, one-to-phi, that is, approximately 1:1.618. A distinctive feature of this shape is that when a square section is removed, the remainder is another golden rectangle, that is, with the same proportions as the first. Square removal can be repeated infinitely, which leads to an approximation of the golden or Fibonacci spiral.

Fibonacci numbers (0,1,1,2,3,5,8,13,21,34...) are a sequence of numbers named after Leonardo of Pisa, known as Fibonacci. The first number of the sequence is 0, the second number is 1, and each subsequent number is equal to the sum of the previous two numbers of the sequence itself.

The Alhambra is a palace and fortress complex of the Moorish rulers of Granada in southern Spain, occupying a hilly terrace on the southeastern border of the city of Granada. Once the residence of the Muslim rulers of Granada and their court, the Alhambra is now one of Spain's major tourist attractions exhibiting the country's most famous Islamic architecture, together with Christian 16th century and later interventions in buildings and gardens that marked its image as it can be seen today.