Short answers, pulled from the story.
The ruins of Hatra lie 40 kilometers northwest of Baghdad and 25 kilometers southwest of Mosul in present-day eastern Nineveh Governorate. This ancient city sat in Upper Mesopotamia as a strongly fortified caravan hub between the Roman Empire and Parthian territories.
Hatra fell shortly after 238 AD to the army of Sassanid king Shapur I in 241 AD. Traditional accounts describe al-Nadirah daughter of the Arab king betraying the city out of love for Shapur before he executed her later due to perceived ingratitude toward her father.
Islamic State forces occupied the area in mid-2014 creating immediate threats to the archaeological site. Videos released by ISIL showed bulldozers destroying monuments shortly after their the 7th of March 2015 announcement claiming graven images violated Islamic law.
Local inscriptions record the name as (Hatra) in Aramaic likely meaning enclosure or fence. A coin struck around 117 AD explicitly labels the site Enclosure of Shamash while Arabic sources refer to it simply as Hatra.
UNESCO designated Hatra a World Heritage Site in 1985 after decades of study. Systematic excavations began only in 1951 by Iraqi archaeologists and an Italian Archaeological Expedition directed by R. Ricciardi Venco made major discoveries starting in the 1980s.