What is the fine-grained topic of the following text: During the time of the Second Temple, Jerusalem began to outgrow all of these local sources of water; the Hasmonean king Alexander Janaeus (104-76 BCE) decided to solve the problem by building an aqueduct – a new technology which had been introduced into the area by the Greeks – to bring water from one of the many springs in the Hebron hills south of Jerusalem. Only return the topic.
Building of an aqueduct in Jerusalem during the Second Temple period