The Oresteian Trilogy is the foundation of tragedy. You need to read it just like you need to read The Odyssey. This was my first time through even though I was familiar with the tropes and scenes through references from other works. The plays are a lot of things, but at its root it's a metaphor for the ascension of society's motivation for good from fear of reprisal as embodied in the Furies, to duty (and fear of its retribution) as embodied by Apollo, to a kind of holy rationality, as embodied by Athene and her counsel. It is ultimately a Whiggish work, convinced society moves ever forward in progress towards harmony.
The one thing that shook me as a modern reader coming to the book in 2017, and a reader who knows the connotations of "maleness" and masculinity in ancient Greek and Roman writing, was that in the climactic scene of The Eumenides, Athene says she sides with Orestes, saying that killing a man as his mother killed his father is a worse crime than killing a woman, as Orestes killed his mother, because of "male supremacy in all things". It's kind of a shit explanation, especially coming from a woman written by a man.
Anyway, read the book. It's embedded in many works of tragedy and worth knowing how the building was built these 2400 years later.