Although Dr. Johnson made it eminently clear that anyone who tires of London must be tired of life, he didn't say what to do if you are tired of tourist cliche's. It's fine for the rest of humanity to swarm to the Tower of London, as an estimated 18,000 tourists will do every day in July, and it's all right for everyone else to play human sardines outside Buckingham Palace as the guards change. But these are the great cliche's of 20th-century travel, and the enlightened traveler feels the need for an excuse to visit them: a maiden aunt who insisted on going, and didn't it turn out to be a lovely excursion after all?

What follows is a compendium of excuses for visiting the most popular tourist attractions in London, the chief reason being the places themselves. There also will be a few suggestions on how to be a tourist. The first suggestion is to admit to yourself that you are one; the second is to revel in that fact.

One sign of being a good tourist is to ask the right questions, even when the answers are lost in the inscrutability of British culture. For instance, what on earth lies behind the impervious expressions on the faces of London's palace guards? The guards on duty obviously aren't saying, but Quartermaster Joe Lowery of the Coldstream Guards, who was on duty in the press office of the Queen's Life Guard, was kind enough to furnish a few hints.

As a soldier and a gentleman, he insisted the sentries possess no secret mantra that allows them to transcend the clicking of cameras.

"It's not as difficult as people think, because you develop a peripheral vision for everything that's happening -- you are simply keeping alert to what's going on around you. It is never boring."

Indeed not, to judge by palace guard lore, which Lowery was only too happy to perpetuate: "At James's [St. James Palace] it is quite isolated and it's not unheard of for women to approach a guard for a chat-up or to leave a note in his boot. Sometimes it's only a leg-pull, sometimes it's not. The uniform seems to attract it."

Contrary to popular impression, the duties of guardsmen do not consist solely of amusing tourists. They belong to the seven regiments of the Queen's Household Division -- the Life Guards and the Blues and Royals, which are the two cavalry units, and the Grenadier Guards, Coldstream Guards, Irish Guards and Welsh Guards -- and when they are not in their temporary role as palace guards they are on active duty in places such as the Falklands and Northern Ireland.

Likewise, the pomp and ceremony of palace guard duty was not devised by some unsung genius at the British Tourist Board, but rather has evolved into state ritual often from quite practical roots. The Trooping of the Color, for example, that most elaborate display of pomp that takes place every June at the Sovereign's Birthday Parade, began in the early days of warfare as a simple expedient for assembling soldiers into units for battle.

There are actually four guard changings daily in London, and although the quintessential ritual is at Buckingham Palace, the changing of the horse guard at Whitehall is more intimately scaled and takes place in a small courtyard with an unobstructed view. The nimble tourist can see both by leaving the Whitehall ceremony just before it ends and going on to Buckingham Palace. As you walk along the Mall to the Palace, you can expect a private encounter with pomp since the horse guards in full regalia will overtake you on their way from Whitehall to the Hyde Park Barracks.

The Tower of London is the most popular tourist attraction in the city, with 2.2 million visitors a year. The first-time visitor will be impressed by the vastness of the place, not to mention its outsized history and lore. The tower is actually a series of edifices and battlements, expanding outward in onion-skin layers from the original White Tower built by the Normans after they conquered England.

As a former royal palace and state jail, the tower provides a neat summary of political glory coupled with the instinct for the infernal. The Crown Jewels are here, and so are such instruments of torture as the Scavenger's Daughter, the Gibbet and the Mantrap. The bones of 1,500 people who died in the tower are interred in the chapel, lending concrete statistics to the best ghost story available in the British Isles.

The narrators of that story are the Yeoman Warders, and if special Oscars are ever given for tourism, they would be a sure bet. (Although they officially spurn the monicker of Beefeaters, derived from the legendary practice of tasting the king's beef for poison in Norman times, the nickname has stuck.) Most Yeoman Warders are former British armed services drill sergeants, which accounts for their prodigious lung power and ability to control crowds on guided tours.

"You give them a bit of romance and always a bit of horror, because they expect that," said Yeoman Warder Joseph Wood. "The key to holding an audience is to get them laughing."

And so the Yeoman Warders stage-manage history as a sort of ghastly farce, with the prominent ghosts of the British past entering the tower through Traitor's Gate and departing to be executed on Tower Hill at the site of what is now a London Underground entrance. The Warders point out the battlement where Sir Walter Raleigh paced during his 15-year imprisonment, and the nearby tower that held Sir Thomas More; they march tourists to the Bloody Tower where the two little princes celebrated in Shakespeare's "Richard III" disappeared and were presumed murdered; they stand on the exact spot where the 71-year-old Countess of Salisbury was executed, but not before she raised her head prematurely from the chopping block and staggered around the platform with the axman in hot pursuit.

We tend to think of tourism as a modern phenomenon, or at least that a certain kind of banality and commercialism belongs to our age alone, and so it is instructive to learn how venerable the tourist impulse is. The Yeoman Warders began allowing visitors to tour the tower in the 1750s, and the sensation of the day was an effigy of Henry VIII that was equipped with a codpiece that could be activated mechanically by pressing a spot on the floor. This remarkable exhibit was eventually removed as an insult to public morals.

Even if Henry VIII is commemorated in tamer fashion today, no one will want to miss his suits of armor on permanent display in the White Tower armory. They belonged to him when he was a rather willowy young man, a mature soldier and finally a stout middle-aged regent -- skinny, normal and fat, they represent the Three Ages of Henry. Also not to be missed is the graffiti that political prisoners carved into the tower walls. In Beauchamp Tower, some of the graffiti is amazingly decorative, but the most pitiable is the simple inscription "Jane" ascribed to Lady Jane Grey's husband Guildford Dudley as he awaited his death and hers at the hands of Queen Mary I.

Perhaps no tourist cliche' evokes an image of greater solidity if not stolidness than the Houses of Parliament, but in truth the public sessions offer real-life drama that rivals anything a tourist could find on the stages of the West End. Most Tuesdays and Thursdays at 2:30 p.m., the prime minister sallies forth in "Question Time" at the House of Commons. Question Time turns the notion of British propriety on its head. The official purpose is to give members of Parliament a forum to question the prime minister on policy, but in practice it is psychological warfare reminiscent of the hijinks of "Tom Brown's School Days."

Opposition MPs are allowed to verbally attack the prime minister, so long as the insults and long-winded accusations are posed in the form of questions. Labor and Tory backbenchers compete with each other and with each speaker in a chorus of jeers, cheers, harrumphs and weird zoo noises. It is far rowdier than an American presidential press conference, but tourists should plan well in advance if they want to attend, since the public gallery seats only about 200 people and priority is given to British citizens.

Another good show is the sessions of the House of Lords. Here the debates move at the pace of the ages, befitting this archaic institution. A visit is worthwhile if only to see the fabulously ornate chambers where a wire net under the ceiling protects their lordships so that chunks of the crumbling roof do not fall on their heads.

Among the peers are former prime ministers and cabinet members, scholars, diplomats, businessmen and dyed-in-the-wool eccentrics, and their primary role is to provide expertise that may help the Commons frame issues. On a given day, you might hear a debate on nuclear arms control, the price of scones or UFOs. You may notice the oddly titled posture of the more ancient lords, but what looks like rigor mortis is only their attempt to listen to the hearing aids concealed in the deep, leather benches.

Then there is Madame Tussaud's, the apogee of tourist cliche' and high kitsch, and at 2 million visitors a year second only to the tower in popularity. Queen Victoria and Telly Savalas are here, but probably the best loved wax dummy is the anonymous guard frozen in foot-weary boredom whose lifelike demeanor never fails to catch visitors unawares. Children will enjoy the re-creation of the Battle of Trafalgar, an exhibit created in 1966 that features a booming recording of cannon fire and a wax figure of Nelson dying in a smoke-filled reconstruction of the ship's hold.

In the Chamber of Horrors, Gary Gilmore is continuously executed every three minutes. Of even greater morbid interest is the death mask of Robespierre, taken from the original wax cast that Madame Tussaud herself made from the freshly decapitated head of the French Revolution's fallen star -- it is kitsch of historical significance.

To maintain topicality, Tussaud's has a staff of 30 sculptors, painters and costumers who can produce a waxen idol in three months at a cost of about $8,000. Each hair on a wax figure's head is applied individually. Armchair social historians should note that the Beatles, removed from exhibition in 1983 after a decade on display, will be back this year by popular demand.

The most ambiguous category of tourist cliche' is that of cathedral and church. The trooping of tourists through Westminster Abbey may not qualify as blasphemy exactly, but one instinctively feels the need to tread softly, and that is nearly impossible to do when a church is also a public monument. Even so, there is a certain rightness in the offhanded nature of tourism. The spirit of Dylan Thomas seems well served by the chatty schoolchildren who traipse to Poet's Corner to see his marker. And as for Oliver Cromwell, the Puritan leader of the Reformation who never compromised in life, it somehow seems to serve him right that most tourists passing through the RAF chapel at Westminster where he is interred walk over his bones without noticing his unobtrusive marker on the floor.

In St. Paul's Cathedral, you can climb the staircase to the Whispering Gallery near the top of Sir Christopher Wren's famous dome. If it is very quiet, the dome's acoustics will enable you to hear a whisper from 107 feet away on the other side of the gallery; more likely, you'll experience the multilingual din and babble of tourists from half a dozen countries, which is as it should be in this cathedral that is the symbol of an island nation at the crossroads of the world. The gallery closes at 3:15 p.m., but the public can sit in the nave for evensong, which begins at 4 p.m. daily in winter and 5 p.m. in summer (the choir is on holiday in August).

For anyone who has played tourist properly, listening to such sweet sounds will be welcomed. You'll feel like a real person again in no time.