Overlooking the Thames, the Houses of Parliament are, arguably, the city's most famous and photogenic sight. The most romantic view of the complex is from the opposite (south) side of the river, a vista especially dramatic at night when the storybook spires, pinnacles, and towers of the great building are floodlit green and gold -- a fairy-tale vision only missing the presence of Peter Pan and Wendy on their way to Never-Never Land.

The Palace of Westminster, as the complex is still properly called, was established by Edward the Confessor in the 11th century, when he moved his court here from the City. It has served as the seat of English administrative power, on and off, ever since. In 1512, Henry VIII (1491-1547) abandoned it for Whitehall, and it ceased to be an official royal residence after 1547. At the Reformation, the Royal Chapel was secularized and became the first meeting place of the Commons. The Lords settled in the White Chamber.

These, along with everything but the Jewel Tower and Westminster Hall, were destroyed in 1834 when "the sticks" -- the arcane elmwood "tally" sticks notched for loans paid out and paid back, kept beneath the Lords' Chamber, on which the court had kept its accounts until 1826 -- were incinerated, and the fire got out of hand. Westminster Hall, with its remarkable hammer-beam roof, was the work of William the Conqueror's son, William Rufus. It is one of the largest remaining Norman halls in Europe, and its dramatic interior was the scene of the trial of Charles I.

After the 1834 fire, architects were invited to submit plans for new Parliament buildings in the grandiose "Gothic or Elizabethan style." Charles Barry's were selected from among 97 entries, partly because Barry had invited the architect and designer Augustus Pugin to add the requisite neo-Gothic curlicues to his own Renaissance-influenced style. As you can see, it was a happy collaboration, with Barry's classical proportions offset by Pugin's ornamental flourishes -- although the latter were toned down by Gilbert Scott when he rebuilt the bomb-damaged House of Commons after World War II.

The building itself, which covers 8 acres, is a series of chambers, lobbies, and offices joined by more than 2 miles of passages. There are two Houses, Lords and Commons. The former has been downsized and reformed by Mr. Blair's Labour party. More than 100 hereditary peers (earls, lords, viscounts, and other aristocrats) failed to win the right to continue to be elected to their seats in the House of Lords. The House of Commons is made up of 659 elected Members of Parliament (MPs). The party with the most MPs forms the government, its leader becoming prime minister; other parties form the Opposition. Since 1642, when Charles I tried to have five MPs arrested, no monarch has been allowed into the House of Commons. The state opening of Parliament in November consequently takes place in the House of Lords.

Visitors aren't allowed many places in the Houses of Parliament, though the Visitors' Galleries of the House of Commons do afford a view of one of the best free shows in London, staged in the world's most renowned ego chamber. The opposing banks of green leather benches seat only 437 MPs -- not that this is much of a problem, since absentees far outnumber the diligent. When they speak, it is not directly to each other but through the Speaker, who also decides who will get the floor each day. Elaborate procedures notwithstanding, debate is often drowned out by raucous jeers and insults.

Other public areas of the 1,100-room labyrinth are rather magnificently got up in high neo-Gothic style and punctuated with stirring frescoes commissioned by Prince Albert. You pass these on your way to the Visitors' Galleries -- if, that is, you are patient enough to wait in line for hours (the Lords line is shorter) or have applied in advance for the special "line of route" tour for overseas visitors during the summer opening (late July-August and mid-September-early October). Tickets can be prebooked by phone or on the Web site; alternatively you can take a chance and buy same-day tickets from the ticket office opposite the Houses of Parliament.

The tour takes you through the Queen's Robing Room, Royal Gallery, House of Lords, Central Hall, House of Commons, and out into the spectacular Westminster Hall. Watch for the "VR" (Victoria Regina) monograms in the carpets and carving belying the "medieval" detailing as 19th-century work. The time to catch the action is Question Time -- when the prime minister defends himself against the attacks of his "right honorable friends" on Wednesday between noon and 2:30 PM (it's also live on BBC2). Overseas visitors should check tour dates and details on the Parliament's Web site. The next best time to visit is either chamber's regular Question Time, held on Monday, Tuesday, and Thursday from noon to 2:30 PM. The easiest time to get into the Commons is during an evening session -- Parliament is still sitting if the top of the Clock Tower is illuminated.

For a special exhibition devoted to the "History of Parliament: Past and Present," head to the Jewel Tower, across the street from Victoria Tower, on Abingdon Street (also called Old Palace Yard), south of Parliament Square. Not to be confused with the other famed jewel tower at the Tower of London, this was the stronghold for Edward III's treasure in 1366. It's also one of the original parts of the old Palace of Westminster and still retains some original beams; part of the moat and medieval quay still remain. Be sure to have your name placed in advance on the waiting list for the twice-weekly tours of the Lord Chancellor's Residence, a popular attraction since its spectacular renovation. COST: Free, £7 summer tours. Tube: Westminster.