St. James's and Mayfair form the core of London's West End, the city's smartest central area. These neighborhoods epitomize the stately flavor that is peculiarly London's—the sense of being in a great, rich, powerful city is almost palpable as you wander along the posh and polished streets.

Neither district is stuffed with must-sees, though there is no shortage of history and gorgeous architecture, but they are custom-built for window-shopping, expansive strolling, and getting a peek into the lifestyles of London's rich and famous, 18th-and-21st-century versions. St. James's is found to the south of Piccadily and north of the Mall, while Mayfair is located to the north of Piccadilly and south of Oxford Street.

Although many will say Mayfair is only a state of mind, the heart of Mayfair has shifted from the 19th-century's Park Lane to beautiful Carlos Place and Mount Street. Even if you head to adjacent Bond Street to bid on a letter at Sotheby's signed by one of the Brontë sisters, or stop in a Graff to price a weighty diamond, the window-shopping is next best to the real thing and is free. Mayfair is primarily residential, so its homes are off-limits except for two satisfyingly grand houses: Apsley House, the Duke of Wellington's home, built by Robert Adam in 1771, and once known as No. 1, London, and Spencer House, ancestral digs of Princess Diana. The district of St. James—named after the centuries-old palace that lies at its center—remains the ultimate enclave of old-fashioned gentleman's London, with the great clubs on Pall Mall along with famed shops for the sartorial peacock.

Despite being bounded by four of the busiest streets in London—bustling budget-shopping mecca Oxford Street to the north, traffic artery Park Lane with Hyde Park beyond to the west, and elegant boulevards Regent Street and Piccadilly to the east and south respectively—Mayfair itself is remarkably traffic-free and a delight to explore. Starting at Selfridges on Oxford Street, a southward stroll will take you through quiet residential streets lined with Georgian town houses (the area was largely developed in the 17th and 18th centuries) and, with a bit of artful navigating, to four lovely greenswards: Grosvenor Square, Berkeley Square, Hanover Square, with its splendid St. George's Church where Handel worshipped, and the quiet St. George's Gardens, bounded by a maze of atmospheric streets and mews. Mayfair is also London's most exclusive shopping destination, with such enclaves as Mount Street, Bruton Street, Savile Row, and the Burlington Arcade. At the western end of Mayfair at Hyde Park corner are two memorials to England's great hero the Duke of Wellington:Wellington Arch and the duke's restored London residence, Apsley House.

The Royal Academy of Arts is at the southern fringe of Mayfair on Picadilly, and just across the road begins more sedate St. James's, with its old-money galleries, restaurants, and gentlemen's clubs that embody the history and privilege of traditional London. You'll get the best sense of the neighborhood just to the south on St. James's Square and Pall Mall, with its private clubs tucked away in 18th- and 19th-century patrician buildings.