Simplify the following text for a Grade 4 native English-speaking person.
Original: The power of L'Aquila was based on the close connection between the city and its mother-villages , which had established the city as a federation , each of them building a borough and considering it as a part of the mother-village . That is also why number 99 is so important in the architecture of L'Aquila , and a very peculiar monument , the Fountain of the 99 Spouts ( Fontana delle 99 Cannelle ) , was given its name to celebrate the ancient origin of the town .
Simplified: That is also why the number 99 is so important in the history of L'Aquila .