Tower Bridge Along the Thames River at Nighttime in London England. (Comstock)

London Bridge is falling down. The words of the popular nursery rhyme came to mind as our boat passed beneath the famous bridge.

Ian Fyfe of Bateaux London, which offers this sightseeing cruise on the River Thames, seemed to be reading my mind.

"It's muddy here," he explained. "The bridge used to fall down, burn down, someone would pull it down to rebuild it."

The first one was constructed by the Romans about 1,000 years ago. Since then, it has been rebuilt at least seven times. In the Middle Ages, the bridge, which was the only structure across the river until the 1750s, even had houses, shops and a chapel on it.

Britons still laugh about the American millionaire who purchased an old London Bridge (which is now in Lake Havasu City, Arizona) in the mistaken belief he was getting the more ornate Tower Bridge.

Many people mistake the two. The current London Bridge is a plain, unembellished version that dates from the 1970s.

About 1 km to the southwest of it is Embankment Pier, the starting point for our two-and-a-half-hour dinner cruise which passes landmarks such as Big Ben and Houses of Parliament, Shakespeare's Globe Theatre, the London Eye and Tate Britain.

Some buildings -- MI5 and MI6, and author Jeffrey Archer's penthouse -- are close to the river's banks, while others such as the Battersea Power Station, made famous on the cover of the Pink Floyd album Animals, are further away but still easy to spot.

In all, we passed (by my count) 12 churches, 13 museums, 11 parks and gardens, and no fewer than 15 bridges. The newest of these is the Millennium Bridge. Locals know it as the Wiggly Wobbly bridge because on opening day it began to sway when about 4,000 people walked across it at the same time.

"A lot of people were very ill," says Fyfe. "The architect said people didn't know how to walk. It was their fault."

But the city decided to close the bridge and spent a further 20 million pounds (about $40 million) on stabilizing the structure.

A better idea would've been to see the bridge from the river. We felt almost no motion at all. The Thames may be tidal, but it's also very calm. And clean.

"We have about 100 species of birds and 120 species of fish in the water," maintains Fyfe. "It's now one of the cleanest rivers of any industrial city."

It's also relatively quiet, at least on this night. I spied only two other vessels -- both tour boats -- on the waterway.

In the old days, before all the bridges were built, boats ferried people and cargo from one side to the other. You can still see steps along the river banks that people used to get to the boats as well as the slipways where horses were used to unload cargo.

HOLIER THAN THOU

London is said to have more churches per square mile than Rome. One of them is St. Bride's, which you can see in the distance just before the handsome Blackfriars Bridge.

Sir Christopher Wren (of St. Paul's Cathedral fame) built the steeple in layers because he wanted a tall, thin structure and it was the only way he could achieve it.

An enterprising neighbourhood baker borrowed the steeple design for one of his creations and started a trend that has continued for 300 years -- the multi-layered wedding cake!

The connection to weddings seems appropriate on Bateaux London, the setting for two to three marriage proposals every month. And one of them, we're told, will be happening tonight just a few tables away.

I wonder if he popped the question just before the high point of the tour -- when the boat makes its famous 360-degree spin near the Tower of London with the sound of Handel's Messiah blaring from the speakers.

"We're a unique vessel," beams Fyfe. "We're the only boat that can do this."

IF YOU GO

If you like the freedom to explore on your own but want the cost savings offered by a package trip, Transat Holidays has several options.

We did the "Package Plus 2 Capitals" which includes flight, accommodations, breakfast, train and transfer. The trip allows you to arrive in one European city and leave from another (we chose London and Paris, but several other combinations are possible).

The hotels are conveniently located, often near major attractions and public transportation. In London for example our hotel was within a few minutes walk of Kensington Palace and the tube station.

Packages start at $1,299 per person before taxes. For more, check transatholidays.com. For details on the river cruise check bateauxlondon.com.