With proceeds donated to ACAPO, this experimental concept is not only a fascinating walking tour, it's an introduction to the true value of our senses.
Walkers are paired with their seeing volunteer, in my case Hugo, blindfolded, before heading off to explore the world of darkness led by Lisbon Walker's Jose, with commentary provided by Carlos.
As we start, Jose translates that we must trust our guides more than 100 per cent. They will not lead us to harm, and the ground won't move beneath our feet, he promises, "unless there's an earthquake".
I put on the comfortable blindfold and close my eyes, as keeping them open would allow my eyes to constantly search out any source of light.
I hold on to Hugo's elbow as we are led forward, instructed about any impending obstacles. Immediately, I am overwhelmed by a sense of vulnerability. Without my lifeline to the elbow, I would probably panic. I feel like an infant taking his first strides. The streets of Alfama are narrow, the alleys small, the stone stairs choppy. Without Hugo, every step would be a challenge - and a potential disaster.
As we make our way down a street, I find myself constantly imagining my surroundings. Is that a church wall? A large hall? A busy market? Other than the murmur of Portuguese, I could be anywhere.
At various points, Carlos pauses to explain the practicalities of his day-to-day life: how he knows what clothing he's wearing, what he imagines a particular colour to look like. He tells us that modern technology, like computers and cellphones, has enabled him to live a more independent lifestyle, and he is grateful for new gadgets.
Alfama is the oldest district of Lisbon, and through the years has been built up into a maze of alleys and squares, lined with small shops or cafes. There's a myriad of smells, sounds and people, and it's the perfect place to awaken sleeping senses.
Thirty minutes later, my hearing becomes more acute.
I become aware of birdsong and footsteps, passing traffic and conversations. My head snaps back and forth as I try to locate the source. My skin also awakens, feeling the sun on my face as I walk in and out of shadow, or brick walls that brush up against my arm as I walk past.
Jose asks us to guess where we are, and in my mind's eye I see a tunnel (it is a corridor), but feel the wind as if standing on a viewpoint (it is a square). After touching trees and leaves, I stop in at a grocer to touch various types of fruit. If a car comes too close, Hugo patiently and calmly repositions me to safety. I simply cannot imagine being like this all the time, and yet millions of people are.
Alfama has traditionally been a poor part of Lisbon, where neighbours would share water or ablutions. In an old communal washing room, Jose explains some of its history - it was one of the few parts of the city to survive a massive earthquake in 1755 - and I find myself clinging to his words, as opposed to drifting off to whatever eye candy I can find.
Slowly I become accustomed to Hugo's nudge, which indicates an obstacle, and begin to walk faster and more surefootedly. After 90 minutes, it is time to remove my blindfold, which I am advised to do in the shade, and slowly.
I hear the rip of the Velcro, and light floods in, stabbing my optic nerve, a dull pain that appears and then quickly vanishes.
Colours explode, requiring me to take a few seconds to compose myself. Carlos is smoking a cigarette nearby; he appears more vulnerable in this sighted world.
The Sensorial Tour was the longest I'd ever been awake, aware and concentrating on a changing sensory landscape, all the while with my eyes closed.
With newfound respect for the visually impaired - and knowledge about an interesting part of Lisbon - I wonder if it's time for other blind associations around the world to take note.
Every city should have a blindfolded walking tour. As a participant, it has to be unseen to be believed.
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Getting there: Air New Zealand, in conjunction with partner airlines, has daily services from Auckland to Lisbon via Los Angeles and London Heathrow. Economy-class airfares start from $3476 a person return.
Further information: To find out more about Sensorial Tours in Lisbon, email lisboa.sensorial@lisbonwalker.com.
* Robin Esrock is the co-host of the Travel Channel series Word Travels.
