This is the first of a two-part series on the author’s recent jaunt to two of the most enduring cities on travellers? lists: London, England and Paris, France.

London and Paris. The names conjure images of romance and history, of royalty and revolution. Until this summer they were places I’d only imagined seeing, but months of planning had paid off. On a cold July evening (5C damp, blustery degrees on the edge of the Atlantic), I found myself boarding a plane for Heathrow and adventure?and more than a few surprises.

Transatlantic flights are hardly what they used to be, but not even congealed airline eggs were enough to dim the anticipation. Our first surprise was Heathrow itself. Back in 2008, when the airport opened its shiny new Terminal 5, the result was chaos. Flights were cancelled and luggage belts were clogged. We weren’t expecting that much confusion, but with almost a million passengers expected to fly through Heathrow that same weekend alone, we were braced for delays.

Not so. After a 15-minute trudge through customs lineups, we found our luggage already circling the carousel and our shuttle driver waiting. And That’s when the true meaning of ?population density? hit.

In Canada, most of us are used to wide open spaces. Our nation covers almost 10 million square kilometres, an area home to just over 34 million people. By contrast, the UK totals just under 244,000 square kilometres, yet holds nearly 63 million people. That’s almost double the population in an area 40 times smaller. If you think you’ve seen traffic in Toronto, you haven’t seen anything like the streets of London!

The famous red double-decker buses are everywhere, but so are something called Boris bikes. Nicknamed after London’s mayor, Boris Johnson, they’re part of the city’s first large-scale public bike-hire plan. Some 400 bike docking stations have been set up across the city, and commuters simply pick up their rides at one station and drop them off at any other.

I’ve seen complaints that the sturdy grey bikes are clunky and less than appealing, but that sure didn’t seem to affect their popularity. As cars and double-decker buses wheeled through roundabouts and switched lanes with a hair’s breadth to spare, Boris bikes zipped between them, seeming to defy the laws of physics as they swirled in and out of sight in the sea of traffic. Businessmen in three-piece suits, college students, seniors?for thousands of people, Boris bikes were just a practical way to get around.

Yet in spite of the constant traffic and streams of buses, something was missing, and it took a couple of days to figure it out: the air didn’t seem polluted. That’s especially surprising since in April of this year London hit its highest air pollution levels since 2003. The only answer I can think of turned out to be the thing that surprised me most.

London is the greenest city I’ve ever seen.

That may not be news if you’ve heard about the many famous parks in the city. Hyde Park alone comprises 350 acres and contains some four thousand trees. But what you may not expect is to be surrounded by tall, stately foliage along almost every street you find.

Not only that, but Londoners seem especially good at tucking green havens into the smallest, most unlikely places. Basement patios, narrow balconies, rooftops: every block we walked held several green gems tucked between buildings or on stoops. On one busy street near our hotel (in the Fulham district), a tiny wrought-iron fence led to an unexpected oasis that seemed to stretch between apartment blocks for miles.

Historic sites, of course, are even more plentiful than trees, and if You’re a first-time visitor with less than six months? free time, be prepared to narrow your must-do list. There simply aren’t enough hours in a week?or even a month?to take it all in.

Besides gaping at major attractions like the Tower of London and Windsor Castle, we found unexpected bits of history everywhere we turned.

Like strolling past a school and noticing a small sign on the wall: ?Beatrix Potter lived in a house on this site from 1866 to 1913.? Or hopping off a bus to land in front of an ancient stone building that Henry VIII built for Anne Boleyn?one that she never saw completed, since he had her beheaded.

We also ventured out of the city and headed for the seaside in Lyme Regis, Dorset, braving the infamous British Rail system along the way. Now, I’ve followed BBC Radio and several UK papers for years, and I’ve heard the general rumbles of discontent from locals. I was prepared for nightmarish train schedules, cancellations, and all manner of transport havoc. But what a treat! The trains were clean and quiet, the routes and incoming trains clearly displayed, and, in a feat the TTC hasn’t yet mastered, the announcements could actually be understood.

For some retail therapy we popped into Harrods, the London retail icon That’s been at its current site, in one form or another, since 1849. Offering valet parking and designers from Alexander McQueen to Yves Saint Laurent, it seemed a sure spot for an hour of hushed elegance and upscale window shopping. Instead, we found a bewildering Alice in Wonderland atmosphere we were glad to escape.

The low ceilings were understandable given the older architecture, but temperatures varied wildly from one department to the next, with air-conditioned chill giving way to stuffy heat upon simply passing through an archway. The landings, all served by a central escalator, were gorgeous to look at but filled with piped music that mingled with competing songs from one level to the next. The effect was a cacophony of sight, sound, and heat that quickly drove us back to the relative sanctuary of the busy streets. Odd, to say the least, for a luxury store?and an experience that suddenly made Wal-Mart look like shopping nirvana!

But if there’s one thing that stood out, that enchanted us beyond the sight of the Thames and the London Eye, it was the city of Bath. Two thousand years ago, Romans came here to relax in the only hot springs in Britain, and the remains of that spa allow visitors to walk on the same stones those ancient footsteps trod.

The city itself, though, was the unexpected marvel. Imagine stepping back in time to land in an 18th-century street, surrounded by stunning architecture and winding, cobbled streets everywhere you turn. From the Assembly Rooms to Jane Austen’s residence to the massive stones at Avebury Circle, Bath is a history and literature buff’s dream?and plans are already in the works for a return trip.

London’s surprises?both good and bad?had barely been discovered before it was time to grab our passports and head for France, luckily missing the recent UK riots by days. Next week we’ll board the ferry to Calais, stroll the streets of Paris, and find out what It’s really like to dine at those famous sidewalk cafés!