It was the fever. Definitely the fever. It was like that scene in Trainspotting when Renton is going through drug withdrawal, when he's been locked in a small bedroom and is gradually sweating the horror out of his system as hallucinations flicker in and out of his consciousness. OK, it probably wasn't that bad but it feels like it now.
I was trapped in a similarly small room, a dank place with peeling wallpaper and a rarely cleaned bathroom. I was ill, but from what I couldn't tell you. It might have been something I ate, or an airborne virus, or my body simply giving up after months of backpacking abuse.
Whatever the cause, I had a serious fever and really should have checked myself into a hospital. Instead, I opted to sweat it out in a Lima hotel room, tossing and turning and moaning at the few people game enough to poke their head in the door to make sure I was still alive.
It lasted a good five days. I tried to get out and see Lima on that trip, I really did, but I shouldn't have bothered. The Peruvian capital became part of my nightmare, the honking traffic hammering my brain, the busy pavements like the hallucinations in Renton's bedroom.
By the time I was getting better it was also time to leave and my only memories of Lima are the pain of illness, the sweating and that horrible room.
It's hard to be objective when you think back on a place you've visited. You don't remember what it's like but rather what it was like for you. Sao Paulo, for instance, might be dangerous and occasionally charmless but after spending a great night out dancing there I'd tell anyone to go. Purely subjective.
Similarly, when anyone has asked me what Lima is like in the last few years I've told it to them straight: horrible. Don't bother. No redeeming features. Dirty and unpleasant. Because that was my experience.
And yet ... And yet here I am back in Lima again and the sun is shining. It's not just shining, it's beaming down from a flawless blue sky, the fog that typically engulfs this coastal city having magically dissolved before my eyes. It's almost as if Lima has something to prove today.
I'm not sick this time; I'm 100 per cent well. If ever my least favourite South American city had a chance to impress, it's today. The bright clear morning is echoing the bright clear feeling in my head and Lima looks, well, nice.
It's actually beautiful. It's buzzing. How did I not discover this last time?
We begin in the historical centre, wandering around Plaza de Armas, the yellow of the colonial buildings striking a contrast with the blue of the sky. Then we take a tour of the Monastery of San Francisco, viewing the old library with its spiral staircases, the fresco-lined walls and the catacombs with their piles of human bones.
We call past Bar Cordano, a 100-year-old purveyor of coffee and booze filled with mostly 100-year-old consumers of coffee and booze, before heading out west to coastal Lima, to trendy Lima.
There's Barranco, the Surry Hills or Fitzroy of the Peruvian capital, a place of art galleries and boutique hotels and achingly cool bars. There's one called Ayahuasca that takes up an entire colonial house and would be wall-to-wall with hipsters if you airlifted it into Australia. Where was this last time I was in Lima? Did it even exist?
The photographer Mario Testino has a gallery here, MATE, which is currently showing an exhibition of his work, a project to capture the costumes of Peru's Andean cultures. It's a smart, modern space filled with smart, modern Limenos. No peeling wallpaper, no dirty bathrooms.
And finally there's Malabar, a restaurant in the swish district of San Isidro. (Lima has swish districts? Apparently so.)
Peruvian food, we're always told, is amazing. That's not my memory, of course. My memory is of tasteless fast food that probably made me sick. But one sweep through the Malabar menu and you realise that something is going on here.
It's fancy food made from local ingredients I've never heard of before.
There's a giant Amazonian river snail. There's heart of palm shredded like spaghetti. There are spikey Andean cucumbers and a gigantic river fish.
The plates are all fantastic visions of colour and texture, like something you might dream up in a bout of hallucination brought on by a strong fever. Except this time it's all real.
Have you ever had a terrible experience in a place that wasn't really due to the destination itself? Did you go back? Would you? Share your stories below.