If you want to mark the start of 'modern' literature, The Canterbury Tales are a strong candidate. About thirty poems and prose pieces, framed as pilgrims to Canterbury telling stories to amuse each other.

In theory, Chaucer is readable by someone fluent in English with a little help. I say in theory, because spelling and word definitions have changed, along with syntax and grammar. Middle English is very different from what we speak, and I'm here to enjoy myself, not to puzzle over a poem with a dictionary. The problem is that poetry in translation always suffers. I read the 2008 Raffel translation, and he does his best, but the result is still middling, if you'll pardon the pun.

Some tales are shockingly good. Anything bawdy, involving sex or butt jokes, comes through just fine. There's a shocking degree of women's agency in some stories, particularly in the Wife of Bath's tale, as well as an exploration of society in the late 14th century. I enjoyed the sheer erudition of Chaucer's knowledge, as his story-tellers shifted between Classical allusions, Christian theology, and contemporary geography to make their points. Apparently each of the narrators speaks in a distinct regional dialect, which doesn't really come through in this. Some characters quote Seneca, some Saint Augustine, some no one at all. The problem is that the good bits are sandwiched between long passages blathering on about virtue. Chaucer may be a deserved classic, and the starting point of modern story-telling, but old does not mean I'm automatically impressed.