The 17th of Tammuz is the beginning of the three weeks of mourning leading up to Tisha beAv.
Among other calamities, the 17th of Tammuz is the day in 70 CE when the Romans broke through the walls of Jerusalem. Three weeks later, on Tisha beAv they destroyed Beit haMikdash, the Holy Temple (the second temple).
This is a dramatization of these events. It is based on the writings of the Jew accompanying the Romans - the historian Joseph ben Mattityahu, a.k.a. Josephus Flavius, without whom we wouldn't know half as much about this period in our history.
Ark of the Covenant - Lost or Hidden Away