John Adams and Thomas Jefferson were American patriots, co-framers of the Declaration of Independence, the second and third U.S. presidents. Sometimes friends, sometimes rivals, they lived in tandem through our nation's difficult birth: Jefferson, the sophisticated Virginia planter, Adams, the Massachusetts yeoman farmer. What is less well-known is that they once went tooling around the English countryside together in a hired coach. David McCullough's Pulitzer Prize-winning Adams biography, the basis for last year's HBO 'John Adams' miniseries, only briefly mentions their trip. But the passage captured my imagination, and I recently decided to follow their route. As it turns out, the itinerary they devised offers as fine an introduction to England as any offered by modern tour companies. In April 1786, they set off on a six-day tour west from London along the Thames River Valley, then north toward Birmingham before circling back to the capital. Of course, I couldn't re-create their itinerary exactly. Some of the places they saw are long gone, in private hands or utterly transformed, like touristy Stratford-upon-Avon, which I had seen before and therefore skipped. But others -- Blenheim Palace and the University of Oxford Botanic Garden, for instance -- remain open to visitors who follow in the great Americans' footsteps, which help to explain their times, very different characters and complex relationship. My retracing of the trip started in Mayfair, one of London's most distinguished neighborhoods, where Adams lived from 1785 to 1788 in the aftermath of the American Revolution. Before the war, Benjamin Franklin had served as an agent of the Pennsylvania colony in the English capital, but Adams was the first U.S. ambassador to the Court of St. James's. He moved to England from France, where he had helped Franklin and John Jay negotiate the 1783 Treaty of Paris, in which the British crown recognized the colonies' independence. His new goal was to forge trade agreements with England, a difficult mission with tensions persisting between the defeated mother country and her erstwhile territories across the Atlantic. To house the embassy and his family, Adams rented a dignified stone house on the northeast corner of Mayfair's Grosvenor Square, still a peaceful urban oasis where nannies push prams and men in pinstriped suits read the Financial Times. Strolling here, I found many reminders of the relationship between Britain and the U.S., including a Sept. 11 Memorial Garden, a bronze statue of President Franklin Roosevelt and a D-Day plaque engraved with the order of the day, issued by Gen. Dwight D. Eisenhower on June 6, 1944. 'Soldiers, sailors and airmen of the Allied Expeditionary Force,' it says. 'You are about to embark upon the Great Crusade. ...The hopes and prayers of liberty-loving people everywhere march with you.' The area remains a diplomatic center, home to the embassies of Canada, Argentina and the U.S., housed in a huge, severe, modern building on the west side of the square. It was designed in 1960 by Eero Saarinen (he of St. Louis' Gateway Arch and the main terminal at Dulles International Airport in the Washington, D.C., suburbs) and widely reviled by traditionalists. Because the U.S. Embassy is often the scene of protests, it is surrounded by a security cordon. Fortunately, its stately old predecessor, where Adams entertained Jefferson and celebrated the wedding of his daughter Nabby to Col. William Smith, still stands across the square, bearing another touching plaque that says, 'John Adams and Abigail Adams, his wife, through character and personality, did much to create understanding between the two English-speaking countries.' (Begin optional trim) After paying my respects at the Adams house, I wandered through Mayfair looking for other American connections, which abound. During World War II, U.S. servicemen frequented Mount Street Gardens, tucked in the neighborhood just south of Grosvenor Square and nearby Grosvenor Chapel, an Anglican church. The park, lined with benches donated by Americans, overlooks the Jesuit Church of the Immaculate Conception where Joseph Kennedy, father of President John F. Kennedy, worshiped while serving as U.S. ambassador to Britain from 1937 to 1940. (End optional trim) Berkeley Square Gardens, another fine Mayfair greensward now decorated with a gazebo, formerly displayed an equestrian statue, cast in lead, of occasionally irrational King George III, who led England through the war with its American colonies. But the monument was removed in 1827, purportedly because the horse's legs buckled under the weight of the rider. Shortly after their arrival in London, John and Abigail Adams were presented to the king, a stiff but amicable occasion. But Jefferson reported an ungracious reception when Adams later introduced him to the monarch and his ministers at St. James's Palace, moving the Virginian to say, 'They require to be kicked into common good manners.' At the time, Jefferson was serving as minister to France, recently widowed and living in Paris, where his path had crossed Adams' in 1784. The friendship the men had forged while drafting the Declaration of Independence in Philadelphia eight years earlier sprang to life again. Abigail, too, delighted in Jefferson's company. Summoned to Grosvenor Square by John Adams in April 1786 to assist in negotiations with the Barbary States of North Africa, Jefferson took time to enjoy the pleasures of London. He attended the theater, shopped, dined in chophouses and studied, with his Monticello estate in mind, the new style of gardening developed by landscape artists such as Lancelot 'Capability' Brown. Adams shared Jefferson's interest in English landscaping, which emphasized a natural look over the formal geometry of French gardens. When negotiations stalled, the two men decided to visit some of these landscaped parks in the English countryside. The inimitable Abagail Adams encouraged the project, feeling that her hard-working husband -- whom she famously addressed in letters as 'my dearest friend' -- would benefit from a bit of fresh air. Was the coach seat well padded? How much luggage did they take? Both men jotted down occasional thoughts but did not keep copious diaries because they were on vacation. We know without a doubt that it was that glorious month, April, in England when the landscape is revarnished in spring green and the scent of lilacs hangs on the breeze. Both men were happiest on their home farms, the one in rocky, hardscrabble coastal New England, the other in the loamy Virginia piedmont. And we know that the friendship between the two men -- whose natures were as different as pepper and salt -- would later be strained by deep political disagreement. Jefferson, a proponent of states' rights, served as vice president during the Federalist Adams administration (1797-1801), then unseated him in the bitterly fought presidential election of 1800. For the next decade, there was only silence between them. That is why their spring jaunt seems a golden moment, as McCullough wrote in his Adams biography, 'the one and only time they ever spent off on their own together.' Just west of London, they toured Claremont Estate, now a fine English National Trust garden surrounded by a moatlike ditch instead of a fence. Jefferson later used this inventive late 18th-century gardening technique, known as the ha-ha, at Monticello. It obscures the separation between the manicured estate and neighboring farm fields, thereby creating long, unobstructed views of the bucolic English countryside. Nearby Painshill Park, another stop on the Adams-Jefferson itinerary, is an even better demonstration of the naturalistic English garden style that was adopted in parks around the world. The cunningly planned vistas, including a vineyard and a 14-acre lake, reveal themselves in succession from a network of paths, winding past surprises such as a faux Gothic tower and Greek temple. I stopped for the night in Weybridge on the River Thames, as did the American statesmen, but found the town's Ship Inn, a hostelry dating from 17th century, too modernized to recall their passage. In their day, though, it was part of a system of relay stations catering to royal mail, private and hired coaches, with postilions to care for the horses while drivers and passengers rested or supped. The next stage of my trip took me north to the Oxfordshire village of Hailey on the edge of the Cotswold Hills. There I stayed at the Bird in Hand, a reasonable facsimile of a coaching inn surrounded by a delightful maze of hedgerow-bordered, one-lane roads. Bumping along in a tiny rental car with about as much pickup as a golf cart, I could almost imagine myself in an 18th-century coach-and-four until a man in a midlife-crisis convertible shot around the bend. I was on my way to Blenheim Palace in the handsome town of Woodstock about 10 miles east of the inn, built by the first Duke of Marlborough and the birthplace of World War II Prime Minister Winston Churchill. The palace, designed in the early 1700s, is a Baroque gem surrounded by a 2,100-acre estate landscaped in 1764 by Capability Brown. Jefferson especially admired the lakes and waterfall, created by a dam Brown built on the Glyme River. From here it is a pleasant 45-minute drive northeast to Stowe Landscape Gardens, on the grounds of an elite boarding school where fellows play cricket in jaunty white suits. Before the school opened in 1923, Stowe was a vast country estate owned by the wealthy Temple-Grenville family whose scion, Richard Temple, began creating the great landscape garden there in 1714. By the time Adams and Jefferson visited, Stowe was in its prime, renowned throughout Europe for its exquisite panoramas and exotic garden architecture, including a rotunda, Palladian bridge, grotto, Gothic ruins and Chinese pavilion. Adams, however, was not keen on the Temples of Venus and Bacchus, noting that people had 'no need of artificial incitements to such amusements.' He vastly preferred Edgehill, tucked under a forested ridge a few miles east of Stratford-upon-Avon, but grew apoplectic when he discovered local people did not know that one of the most important battles of the English Civil War took place there in 1642. Today people walk their dogs on the battlefield and drink ale at the Castle Inn above it, seemingly as unaware of Edgehill's significance as ever. The travelers were headed home by the time they reached Oxford, although they stopped to see the university's botanic garden, whose first incarnation was completed in 1633 on the River Cherwell. Jefferson tipped the gatekeeper generously, but neither man recorded his impressions. Adams probably was eager to see Abigail, but Jefferson's wanderlust was unabated. He did more sightseeing in London before taking his leave weeks later. I stopped to open my umbrella by the Herbaceous Border, a riot of flowers, and thought of the fair English sights I had seen in the footsteps of Adams and Jefferson, fellow travelers, trusty guides. 