Cerro Tololo is home to B. One of the world's largest observatories
<span>. built dams to provide for irrigation</span>
irrigation was used to farm lands that were originally arid and semi arid<span>4. converted bad land into agricultural fields</span>
<span>these bad lands otherwise ARID AND SEMI ARID were successful reclaimed through irrigation methods.
</span><span></span><span>5. invented new farming methods
</span> improvements in agricultural techniques and tools bolstered the agricultural sector making it one of the important source of taxes for the dynasty.
Smallpox took its toll on the Aztecs in several ways. First, it killed many of its victims outright, particularly infants and young children.
Commonly referred to as the "Pennsy," the PRR was headquartered in Philadelphia<span>, Pennsylvania. The PRR was the largest railroad by traffic and revenue in the U.S. for the first half of the twentieth century.</span>
