The city of Pisa was at the beginning a simple but important Italian seaport. With its growth, so did its religious buildings. Its fame and power grew gradually over the years, as the people of Pisa were involved in various military conflicts and trade agreements.
Answer: a layer in the earth's stratosphere at an altitude of about 6.2 miles (10 km) containing a high concentration of ozone, which absorbs most of the ultraviolet radiation reaching the earth from the sun.
Explanation:
