The Church History of Eusebius, the bishop of Caesarea was a 4th-century pioneering work providing a chronological account of the development of the early Christian Church from its beginnings to the 4th century. It was written in Koine Greek, and survives also in Latin, Syriac and Armenian manuscripts.
Eusebius had at his finger-tips the Theological Library of Caesarea and made use of many church documents, acts of the martyrs, letters, extracts from earlier Christian writings, lists of bishops, and similar sources, often quoting the originals at great length, some of which have only survived in his work. For example he wrote only Matthew composed his Gospel in Hebrew, but that this translation is lost.
This app version of his history includes the "Life of Constantine" and "Oration in Praise of Constantine". The footnotes are linked to the text. Also all Bible references are linked the World English Bible for easy reference.