Final answer:
Mortimer Wheeler excavated the Indus Valley Civilization in Pakistan, focusing on the cities of Harappa and Mohenjo-Daro, known for its Great Bath.
Step-by-step explanation:
The ancient civilization that Mortimer Wheeler excavated while in Pakistan was the Indus Valley Civilization, specifically the cities of Harappa and Mohenjo-Daro. These sites, including Mohenjo-Daro in Sindh province with its famous Great Bath, are some of the most well-known excavations symbolizing the advanced urban culture of the Indus Valley Civilization, which dates from 3300 BCE to 1300 BCE. Mortimer Wheeler conducted significant archaeological work in South Asia in the 20th century, and his excavations helped to highlight the complexity of this ancient civilization.