Belvedere (The Observatory)
Toma and Tsuchimikado investigate the history of a sacred artifact as they try to figure out what Oriana’s plan is. When they discover they have only until nightfall to stop her from enacting an evil plot, the battle for the future of Academy City begins!
Aired 24/12/2010EP 12 - Belvedere (The Observatory)

2010
A Certain Magical Index II
Index is still a fugitive, and many powerful magical organizations and individuals want to take her to use the books in her memory, eliminating her in the process. War between those organizations is also starting to emerge. Index can only rely on her friend Touma, who has always protected her, along with Misaka and other friends from the Academy.
(Source: Anime News Network)