The Nea Ekklesia church in Constantinople, on which many later cross-in-square Eastern Orthodox churches were based, was consecrated. Nea Ekklesia: The Nea Ekklēsia was a church built by Byzantine Emperor Basil I the Macedonian in Constantinople between 876 and 880. It was the first monumental church built in the Byzantine capital after the Hagia Sophia in the 6th century, and marks the beginning of the middle period of Byzantine architecture. It continued in use until the Palaiologan period. Used as a gunpowder magazine by the Ottomans, the building was destroyed in 1490 after being struck by lightning. No traces of it survive, and information about it derives from historical accounts and depictions. May 1, 880. Wiki link