That’s how fast this city gets into your system.

It might happen the first time you walk along the Thames and catch a glimpse of the world-renowned silhouette of the Houses of Westminster and its clock tower, Big Ben, or the Tower Bridge or the Tower of London. It might happen when you first pull up to a pint in a warm, wood–paneled pub, or catch yourself looking the wrong way before crossing the street. It almost surely will happen the first time you board an Underground train and hear the stern, automated admonishment to “mind the gap!”

But it will happen. You will get caught up in the sights and rhythms of London…and that’s a good thing.

Aside from being one of the world’s great urban attractions in its own right, London is a great starting point for your first venture into international travel. Since the British speak English — at least in theory — you’ve got no language issues to jolt you out of your comfort zone on your very first venture away from American soil, as opposed to Tokyo or Cairo or Moscow.

At the same time, London — indeed, all of the United Kingdom — is just “foreign” enough to give you the sense that, like Toto, you are now a long way from Kansas.

London has five major airports. Your flight is likely to take you into either Heathrow or Gatwick. Getting out of the airport and into central London is the first place you’ll encounter the most important reality of visiting Britain: Their pound is worth a lot more than our dollar.

Unless you either own a bank or recently robbed one, do NOT plan on taking one of London’s famed black taxis into the city. The fare may send you into cardiac arrest.

It’s worth repeating: Everything is more expensive in London, but that’s doesn’t put it out of your reach. Save your coins, budget carefully and you’ll be fine.

Both Heathrow and Gatwick have express trains which will get into into one of central London’s train stations, from which you can make easy — and much cheaper — connections to where you’re staying. But Heathrow has an extra advantage for travelers, its own subway connection.

The Piccadilly line on the London Underground — also known to Londoners as “The Tube” — takes you straight from Heathrow airport into London’s South Kensington, just north of the Thames near the West End. Not as fast as a taxi, but almost as convenient and infinitely cheaper.

No one will mind if you get on the subway with your luggage; travelers do it all the time.

South Kensington is custom-made for first-time visitors to London, or first-time travelers in general. It’s got everything you need, and I do mean everything! It’s now my de facto London neighborhood. There are plenty of hotels, but I prefer short-stay apartments like the Oxbridge Apartments, right around the corner from Cromwell Road, sandwiched in an easy 10-minute walk between the Gloucester Road and Earls Court stations, and directly across the street from our favorite supermarket in all the world, Sainsbury’s.

Lemon curd, Irish oatmeal and clotted cream (don’t let the name trip you out; it’s actually quite good) for breakfast, Twinings teas any time of day, biscuits and Seriously Strong–brand cheddar cheese for late–night snacks while watching the BBC (it’s Scottish, delicious and totally lives up its name), and chicken tikka masala 24/7 from the deli.

You have to bag your own groceries in Europe, but who cares?

In the three blocks between the Gloucester Road subway stop and the apartment, i found:
* four hotels
* two supermarkets, Sainbury’s and Waitrose, and a small Tesco market
* a half-dozen great Italian, Indian and Thai restaurants
* a coin laundry
* an Internet cafe
* a bank with four ATMs outside
* a Post Office
* A tourist shop selling memory cards, camera batteries, phone cards, umbrellas, luggage and anything else you’re likely to have lost, forgot to pack or broke.

A turn up or down Gloucester Road will take you to more restos, pubs, bookstores and shops, not to mention Kensington Gardens, a beautiful, serenely green park that was home to Princess Diana until her death in 1997. The mountain of bouquets you saw on TV, piled up at the Kensington Palace gate by thousands of mourning Londoners, was here.

Three blocks to the east and you’re at the Gloucester Road stop for “The Tube.” Three blocks the other way and you’re Earl’s Court, with its own handy Tube stop. Between the two, navigating the whole of London is “easy-peasy!”

Interested in history? London is one of the European capitals that’s practically buried under it. At the feet of Edwardian and Elizabethan palaces and cathedrals are the foundations of buildings erected by the Romans. But this is the same city with ultra-modern architecture reaching to the sky, including the London Eye and a city hall that looks like a giant, precariously balanced glass egg.

It’s almost as if antiquity and modernity are forever jostling each other for elbow room.

A vibrant theater scene. A restaurant scene in constant motion that is busily erasing the memory of British food as the horror of Europe. A music scene more diverse than anything you will hear on American radio or MTV, and a club scene to match. If you’re fascinated by fashion, you’ll find yourself in one of its world capitals. And every race, nationality, culture and language is represented here…in abundance.

The British writer Samuel Johnson knew of what he spoke when he said, “When a man is tired of London, he is tired of life.” One way or another, London gets into your system and refuses to let go. Resistance is futile.

Plan on returning.