If you have always wanted to read Virgil, Homer, Julius Caesar, and were not inclined to begin with a chronological survey of culture, history, philosophy, this book will enliven and make intelligible your reading. One literary help for me was to be able to look up the name of a character, geographical location, or common noun, and find enough information to make a whole text intelligible.
While Oxford Classical Dictionary covers subjects in greater detail, this volume is a direct help in reading Greek and Latin texts in translation.