Steve McKenna takes the ferry to an outpost of ageing charm across the river from Buenos Aires.
The Argentinian couple have come across from Buenos Aires for the day. They're artists, they say, and Colonia del Sacramento is the perfect place to express their talents. They've brought their chihuahua, paintbrushes and blank canvases with them, as well as flasks of hot water to top up their tubs of mate.
This bitter, herbal tea-like substance is sucked through a straw and, along with watching soccer and devouring massive steaks, sipping mate is a passion shared on both sides of the River Plate.
Argentinians and Uruguayans have much in common, and although they have a rivalry, it's a friendly one – unless you happen to tell Uruguayans their best attractions are in Buenos Aires' backyard. Say the same thing to an Argentinian as I have said about Colonia del Sacramento and they laugh.
Colonia is just an hour's ferry ride from BA. Each morning hundreds of people come over from the bustling Argentinian capital, spend the day in Uruguay then, as sunset approaches, take the return ferry.
Considering Colonia promotes itself as a place where you can "step back in time amid cobblestone streets laced with beautiful old buildings", I honestly feared it would be overrun with visitors. How wrong I was.
It's popular but it remains remarkably pretty, laid-back and unspoiled. As a bonus, beggars, overbearing street vendors and con artists are nowhere to be seen.
While you could squeeze Colonia's highlights into a day, I decide to linger and soak up the atmosphere. Cobblestone streets are, of course, everywhere. I struggle to find a road in old Colonia that isn't heavily paved with chunky flints. The streets are also lined with pastel-shaded mansions, many boasting stucco ornamentation, shutter windows, grilles and balconies.
Towering trees and plants blessed with pink, lilac and violet petals only add to the exquisite scenery, as do vintage parked cars with flat tyres and flowers growing from them. It's no wonder artists are drawn here.
The oldest part of Colonia, the Barrio Historico, hugs the edge of a peninsula that juts out into the muddy River Plate (River of Silver), about 50 kilometres from Buenos Aires. In the 17th century, Buenos Aires was an up-and-coming Spanish port city. Galleons and frigates from Britain and the Netherlands were circling the river, looking for a rival place to set up camp. A Portuguese seafarer, Manuel Lobo, realised the strategic importance of the Colonia peninsula and, in January 1680, he stuck the red- and green-flag in it.
Lobo's Lisbon masters wanted somewhere from which they could smuggle contraband goods into Buenos Aires but Colonia's formation didn't go down well with the Spaniards and the fledgling Portuguese colony was soon overrun.
This heralded a tug of war between the two mighty European nations and, over the next century, through a mix of war and diplomacy, Colonia changed hands between Spain and Portugal seven times. In 1788, Spain decided enough was enough. There would be no turning back for Colonia. It was Spanish and it would stay thus – until 1825, when the nation of Uruguay was formed as a buffer zone between the increasingly powerful Latin American duo of Argentina and Brazil. Fiercely independent Uruguay's motto is now "libertad o muerte" (freedom or death).
There's no hint of any warmongering in Colonia today, though. The Barrio Historico is a haven of peace and quiet, especially compared with the relatively noisy, traffic-filled modern part of Colonia. There are a few standouts in Colonia, not least the reconstructed 19th-century lighthouse, which looms above all and sundry, alongside the ruins of a 17th-century convent.
My favourite spot, though, is the delightfully named Calle de los Suspiros. It translates to Street of Sighs, although these days it seems to induce smiles. It's an authentic alley dating from the first Portuguese occupation.
Lots of little museums are spread across Colonia, including ones specialising in azulejo tiles (a Portuguese tradition). Seafaring maps, pottery and period clothing also decorate these small but absorbing cultural spots. Elsewhere in town, a handful of boutiques and art galleries seduces passing tourists, while there are a staggering number of dining spots, most with small armies of umbrellas covering tables and chairs outside.
Especially popular are parrillas, which offer swathes of barbecued beef, pork and chicken. High-brow eateries serve delicious seafood, while a particularly fine spot is El Torreon. Set in an old tower overlooking the water, it's a perfect place to sip a cocktail and watch the sunset. As I glimpse yachts gliding past – and, from the corner of my eye, the ferry chugging back to Buenos Aires – I'm delighted I decided to stay put in this charming place. Colonia may be small but it leaves a big impression.
Double rooms at the delightful, 150-year-old Posada Manuel de Lobo are priced from $US80 ($87) a night. See colonianet.com/posadamdelobo.