MARTIN PADILLA DIPS a paintbrush in a jam jar and pauses to inspect 10 days of work Flanked in his workshop by a statue of a saint and a pet tortoise, Martin squints at depictions of his hometown of Cartagena on which the paint is not yet quite dry There is the mustard-yellow facade of the clock tower, under whose arches cigar salesmen idle in the midday heat There is the dome of St Peter’s church, mingling with the masts of moored ships and the tallest palms in the parks. Beyond the crumbling battlements, dolphins leap from a blue sea, ‘Cartagena is a city of strange energy’, he says, ‘And this energy brings me happiness. I feel proud when I paint my city. It’s like when a musician plays his first note – as soon as I make my first brushstroke, I am completely absorbed!’

Martin isn’t painting these scenes on paper, on canvas or on a wall. He is painting them on a bus. And not just any bus, but a chiva – one of the vintage technicolour vehicles that are the kings of Colombia’s Caribbean road network, part public transport, part miniature – carnival. They are given names, flashing lights and mini-murals. They are variously put to use as mobile discos, as transport for people, shipments of coffee or (in rural areas) protesting chickens, goats and pigs. Wherever they go, they are as ambassadors of the Colombian Caribbean: extroverted and fun-loving.

‘Every bus has a character,’ explains Martin, resting his arm on the bonnet. ‘This one is called La Todo Bien (‘It’s All Good’). The whole idea is when you see it drive past it makes you smile.’ Chivas can often be found lapping the battlements of Old Cartagena – fortifications built to repel pirates since the town was founded in the 16th century. Rusting cannons that once protected shipments of gold bound for Spain are now pointed at passing traffic. Ramparts once besieged by Sir Francis Drake are today besieged by children flying kites. But the bulky chiva is of no use in navigating the narrow alleyways of the city within.

Walking into the city, you temporarily exit 21st-century South America and enter a place that seems adrift among both continents and centuries. A few streets feel like 19th-century Europe: rows of townhouses where bougainvillea sprouts through the stonework, with little balconies warped by centuries of Caribbean heat. At other times Afro-Colombian culture takes over: Map ale dances strike up nightly in the square of Plaza de la Aduana, the rhythms said to originate from Angola. And then there are indigenous crafts for sale in the arcades – woollen satchels of a kind woven here before Europeans and Africans even knew of the existence of another continent over the Atlantic.

As well as painters like Martin, poets, musicians, sculptors and philosophers have all sought inspiration from Cartagena’s cultural crosscurrents. None are better loved than Gabriel Garcia Marquez, who studied and lived in Cartagena and who explained all his books contain ‘loose threads’ of the town. He borrowed its streets for the classic 1985 novel Love in the Time of Cholera- a story of two lovers kept apart throughout their lives in the same city. With only a bit of detective work you can recognise the almond-tree-lined Plaza Femandez de Madrid as the fictional Park of the Evangels, where the love sick young Florentino Ariza hopes to catch sight of Fermina Daza.

You can identify the quays from which Florentino and Fermina cast off on their steamboat journey through the swamps and forests of the Colombian interior in the final pages of the book And, walking anywhere in the town, you can understand the sentiment of Dr Juvenal Urbino, of whom we are told ‘all his reserves of passion were concentrated on the destiny of his city which, he said with great frequency and no second thoughts, had no equal in the world’.