Written to the chain on 06 Apr 2013, block 230,009.
Bitcoin's founding document, stored inside Bitcoin itself. The 184,292-byte PDF was split across the fake public-key fields of a bare-multisig transaction in 2013 — a technique that burns the coins it uses, so the sender paid real money to make the paper as permanent as the ledger it describes. Every full node has carried a copy ever since, whether or not its operator knows.
Bare multisig outputs list several public keys and say how many signatures are needed to spend them. Uploaders discovered that the public-key slots could carry arbitrary bytes. A transaction can include many such multisig outputs, each carrying one or more fake key-sized chunks.
More about P2FMSEvery byte shown here was read from these transactions. Open one in a block explorer to check it yourself.
