Ok, writing is not my forte but I'll bite. English is my second language so I'll probably make some grammar mistakes but here we go:
So, my favorite thing about the way Lana writes is that a particular song can have several meanings and interpretations, with several layers to be uncovered.
Arcadia in particular is a loaded word - at first glance, it's a city in LA county and Lana reinforces that by comparing her body to a map of LA.
But since I'm not from the USA, the first thing that popped in my head when I read the title Arcadia was Arcadism. The name derives from the greek utopian myth of Arcadia, an idyllic place which was a safe haven for poets and artists in general. It is one of the most popular literary schools in romance languages, specially in lusophone countries such as Portugal and Brazil. Arcadism was a reaction to the previous literary school, which was Baroque, known for its grandeur and excesses. As Lana fans we may be familiarized with Baroque Pop which was one of the genres of her albums Born to Die, Paradise and Honeymoon. Lana started with a "new sound" and a "new way of writing" after Lust for Life, so I believe that naming a song Arcadia is her way of saying that she is really distancing herself from exaggerations in her music and in writing. Thus, she is becoming more and more personal, real and brutally honest with each album.
One of the main characteristics of Arcadism is more simple language and exaltation of country life/a simple life in detriment of urban life/materialism.
Arcadians cut useless aspects of life and seek simple things, rich in spiritual meaning. I find that to be true for most of Blue Banisters' songs - many allusions to nature, Lana wishing for simplicity and making more mundane observations, simple songs that read almost as lullabies (specially Cherry Blossom and Sweet Carolina). This was her Arcadian moment.
This is the meaning that Arcadia always held to me personally. But a few days ago, I came across a painting called "Et in Arcadia Ego", which can be translated to "Death too is in Arcadia".
Again, many possible interpretations, one of them being a mement mori: death will come for everyone even if they live in a perfect place such as Arcadia. There is a play inspired but this painting - Arcadia by Tom Stoppard. One of the most proeminent themes of the play is time as a steady march to death. This made my reflect on the line:
"In Arcadia, Arcadia
All roads that lead to you are as integral to me
As arteries that pump the blood that flows straight to heart of me"
And I interpret that in 2 ways: firstly, it's Lana saying that being a poet is as integral to her as her own heart. Secondly, that all roads in life lead to inevitable death, so living is essentially walking towards death. The way she uses the heart/blood metaphor which is the essence of being alive is so beautiful. So in my own personal headcannon, Arcadia is like a sequel to Born to Die (the song), even though Lana said "listen to it how you listened to Video Games", I personally listen to it like I listened to BTD.
I needed to write at least a thinkpiece about this song because I've loved it since it came out. Imo it's one of her most well written songs and nothing will ever change my mind about that.