This article appears in Volume 20: The Homelands Issue.

A A family is dressed up as a group of ski tourists, desperation disguised under thick coats. One possible escape route has already closed and a second is being sought. The mother has never skied before, but she'll be expected to slide through snow over the border and on towards safety. The daughter they have with them - Eva - is in her late teens. Their younger one - Vera - is at a school in Switzerland. It's their father who's orchestrated this concealed flight, rushing back to Prague, trying to hide his panic. It's 1948, the Communist coup d'état has just taken place and he knows that he's being followed. By now the fact that they've rapidly fled their home - through a rear window because the front of the building is under surveillance - has probably been discovered. They need to get out of Czechoslovakia, and fast.

My paternal grandmother Vera became a refugee at the age of 16. She lost her home city as well as her language, friends, country and nearly all of her possessions in a single day. The family sought asylum in Ireland before eventually being allowed into the UK, where Eva very sadly died of leukaemia at the age of 19. Babi (Czech for grandma) went on to train at The Royal Academy of Dramatic Art as an actress, living and working in Britain, America and Germany. She didn't see Prague again for nearly three decades, by which time my dad was ten.

And here I am, standing on the street where it all began. A street like many others in the city, with pastel buildings and old windows with the paint peeling off. A few of these windows once framed my grandma's face. During the Second World War a bomb fell not too far away from here. My grandma, then a child, was having her hair braided by her grandmother. She claimed that she'd never seen the old woman - who usually could only move slowly, cane in hand - bolt so fast down six flights of stairs to get to the cellar. Once this place was home to glamour and parties, to homework and family meals, to fear and plans and bickering, and nights spent quietly hunched over the radio. Then, on that day in 1948, it was left behind.

Only there's a problem. I can't work out which apartment they lived in. Was it the blue building or the grey one? I know that it's about halfway down the street, on the side where the floors stretch up high. Maybe it doesn't matter. Even without identifying the exact address, I can already better place the stories that I grew up with. They have a setting beyond the half-formed images in my head. Somewhere on this street is where those stories began.

I can't recall a point when I didn't know about Prague. Our Babi is a seasoned storyteller, and I've always been fascinated by the twists and turns of her life. However, for some reason I'd never visited her city. In the absence of actual experience, it mainly existed in details relayed by her - men selling live carp from big barrels of water on the street, girls dressed in white processing around churches, a state funeral seen from a family friend's ornate balcony, Vera's older sister, Eva, pinching her legs under the dinner table, the shiny black boots of the Gestapo officer searching their apartment during occupation. These details, which are added to every time she unravels another tale, are a mixture of entrancing, horrifying and cinematic, the Second World War seen through a child's eyes. This year I finally decided that it was time to map her version of the city on to its present-day incarnation - to flesh out these stories further, and see where she spent her formative years for myself.

I hadn't anticipated it being this beautiful. Stupid, I know, but it still feels like a revelation compared to the stock images on Google and the few monochrome photos from Babi's youth (it's amazing how different our perception of space is when it is cast in black and white). The city brims with colour. There are green graveyards, dappled parks, rococo churches dripping in gold statues with frescoed ceilings, terracotta roofs, doorways guarded by carvings of half-clad women and street after street of buildings in confectionary colours - lemon, mint-green, sugarmouse-pink, pistachio, peach, chocolate and gobstopper-blue. Take away the cars parked on the cobbles and the odd tattoo parlour or mini-market and, in some pockets of the city, it would be easy to imagine that you'd rounded a corner and tumbled straight into the 1920s. Scrap that. The 1820s. Of course, it helps that this is a summer visit. The tree-lined avenues are already hot when we set out at 8AM, and the smell of lime blossom is everywhere. Every time we hit the river Vltava, criss-crossed several times each day, I'm struck by how fiercely it sparkles. And on the evening when we head to the observatory at the Žižkov television tower, I marvel at the city seen from on high, at the way that the low light brushes everything with gold.

We mainly explore on foot. I'm here with my photographer-friend, Susannah, and on the first day we manage to cover 17 miles as we wind from bridges to hills to alleys to grand buildings to the odd, leafy stairway. We visit the Jewish cemetery, with its higgledy-piggledy graves like rows of broken teeth, search in vain for a hidden flea market in a courtyard that apparently exists somewhere near the national library, and have a pit-stop to eat slabs of strudel in Petřín Gardens, where couples, families and gaggles of friends spread out on slopes between the trees.

Susannah soon turns out to be the ideal travelling companion. I love to watch her with her Rolleiflex camera - the way that she stops, sizes up an image and finally clicks the shutter. She does it with such grace. As well as a good eye, Susannah also happens to have an impeccable nose for the best cafés in the vicinity. On the first day we practically take up residence in the Café Savoy, which sits a short stroll away from the Most Legií (Legion Bridge). Despite being fully booked we manage to snag a seat on the bench outside, eating breakfast al fresco while looking at the trams rattling past. The coffee, fresh bread, boiled eggs, thick slices of ham and emmental prove to be the ideal fuel for further exploration. Later we return for lemonade. And in the evening, weary with stomping, we sheepishly turn up again to ask if they might have room to squeeze in two for dinner. The waiter recognises us and we are duly led to a table.

As we eat wiener schnitzel surrounded by white tablecloths and chatter, we talk about the process of retracing history. It's an imprecise art, requiring a strange balance between known scraps and imagined story. Or rather, an acknowledgment that drawing clean lines between these points can be impossible. We are chasing fragments - ones that, as with all memories, will have shifted and twisted and calcified over the years. In between these fragments there are vast gaps in my knowledge. Susannah asks questions about my grandma's family that I can't answer, or can only hazily recall. I'm sure that there are bits that I'll have accidentally added in too, or got wrong in the retelling.

I think more and more about this process as the stay goes by. At some points I feel as though I have split-screen vision. Here I am, taking in the hidden delights of the library in the Strahov Monastery, where it costs 50 koruna (just over £1.50) to take pictures - it's absolutely worth it, because the light falling on the rows of books and glass cases full of sea creatures and butterflies is too spectacular to go uncaptured - or stopping to study the elaborate alcoves in the Vyšehrad cemetery, where so many poets and sculptors and composers were laid to rest. At each juncture I wonder whether Babi ever lingered here, and what it was like through her eyes. How different did it look then? What was the city like under occupation? And before? And after? At Vyšehrad, perched on top of one of Prague's many hills, I imagine a younger version of my grandma also standing there, staring over the sweep of her city.

At other points I have a clutch of named locations. On the first day we battle through tourists to the bottom end of Wenceslas Square, where my great-grandfather's shop used to be. Ever the canny entrepreneur, he began selling radios after the Second World War, and was highly successful. Later we stand in the Old Town Square, rounding on the famous medieval astronomical clock just before 1PM. The crowds are huge, all waiting for the little procession of mechanical men that appear on the hour. Somewhere in the vicinity my grandfather used to have offices, but again, I can't work out exactly what building to look at. All I have are rough approximations, and the knowledge of how cities are always shifting - forever being built up, torn down and remade. Even the ones that still look perfectly historically preserved.

Other places prove more tangible. On the second day we spend the morning in Vinohrady, the area where Babi grew up. First there's the The Church of St Ludmila in Náměstí Míru. Babi was christened here. It's not open to the public in the morning, so we hover in the atrium and squint through glass at the patterned columns and red carpets. I think this is the church that Babi's older sister Eva used to bunk off from - heading diagonally across the square to the Valdek cinema to watch films instead (that building is now an office block, although the name remains). Occasionally she let her younger sister tag along. I'm not sure if it's also the church where Babi made up sins to tell the priest, whispering in the confessional booth and painting her life as far more wicked and exciting than it actually was. I hope that it is.

The Vinohrady Theatre opposite the church, with its winged sculptures on top of the building, depicting bravery and truth, invites a similar balance between solid facts and embellished possibilities. There Vera and Eva sat to watch performances of fairytales, the perfectly presented children of an important businessman. Babi also took part in a poetry recital contest on that stage, and won. However, I don't know if the verse she performed really did start with the Czech words that translated mean "for a little love, I would go the end of the world", or whether I've just parachuted in that reference because I know how much she loves that poem.

Later, on the way to the brilliant Café Sladkovský, where the food is superlative and the interiors look like something dreamt up by Wes Anderson, we go through another gorgeous park. I point out the vineyard on the slope, dark-green leaves rustling. It's only when we're sitting in the café that I check Google maps and realise that we're only a six-minute walk from Babi's old street. We've been circling it all day. That park was the one where her playgroup met when she was a child. The vineyard on the hill - well, she's told me about it before. The story retrospectively makes the space more charged.

By the final day my head is awhirl with images and narratives and questions about how on earth to distil this all down into words. We wake early, Susannah suggesting a 5AM start to get a good look at Charles Bridge before it's overwhelmed with tourists and selfie sticks. We catch the metro in. The streets are deliciously quiet. After the first day's hot bustle of tourists it's paradise, but as we approach the bridge we realise that we're not alone. Ahead of us a bride stands, a column of white froth against the grey stone. Behind her there's another. Then, in the distance, another, all arriving with their grooms and their own photography teams in tow. As we cross the bridge I count them as though they're magpies, seven in total. Although that's the wrong analogy, I realise - they're more like swans, preening in the soft glow before the sun burns bright.

What a sight, so manufactured, yet so captivating. A world away from my grandma's city, but the bridge remains. It's been there since the beginning of the 15th century, and millions of feet have passed over it since then. Hundreds of years' worth of stories and memories and trauma and wonder. And now the happy couples. And us. All visitors in the morning light. All people constructing our own stories from the stones underneath our feet.