7 Best Sights in The Thames Valley, England

Six miles east of St. Albans, this outstanding brick mansion surrounded by lovely formal gardens stands as a testament to the magnificence of Jacobean architecture. Robert Cecil, Earl of Salisbury, built Hatfield in 1611, and his descendants still live here. The interior, with its dark-wood paneling, lush tapestries, and Tudor and Jacobean portraits, reveals much about the era. The beautiful King James Drawing Room is a vision in ostentatious grandeur, with its gilded ceiling and portrait-covered walls. By contrast, the Chinese Bedroom is a charming example of the later 19th-century infatuation with Far Eastern design. The intricate Marble Hall, with its elaborate carved wooden panels, is one of the most impressive rooms in the house, although perhaps the building's finest single feature is the ornate Grand Staircase, with carved wooden figures on the banisters. The knot garden, near the Tudor Old Palace, where the first Queen Elizabeth spent much of her youth, is a highlight of the West Garden. Wednesday is the only day the East Garden, with topiaries, parterres, and rare plants, is open to the public. The Park has lovely woodland paths and masses of bluebells. There are various markets, theater performances, and shows throughout the season, including open-air film screenings and, occasionally, Elizabethan banquets. Check the website for the schedule.

Attention all Muggles: this spectacular attraction just outside Watford immerses you in the magical world of Harry Potter for hours. From the Great Hall of Hogwarts—faithfully re-created, down to the finest detail—to magical props beautifully displayed in the vast studio space, each section of this attraction showcases the real sets, props, and special effects used in the eight movies.

Visitors enter the Great Hall, a fitting stage for costumes from each Hogwarts house. You can admire the intricacies of the huge Hogwarts Castle model, ride a broomstick, try butterbeer, explore the Forbidden Forest, and gaze through the shop windows of Diagon Alley. The Hogwarts Express section—at a faithfully reproduced Platform 9¾—allows you to walk through a carriage of the actual steam train and see what it's like to ride with Harry and the gang. Tickets, pegged to a 30-minute arrival time slot, must be prebooked online. The studio tour is a 20-minute drive from St. Albans. You can also get here by taking a 20-minute train ride from London's Euston Station to Watford Junction (then a 15-minute shuttle-bus ride, free with a valid Studio Tour ticket). Via car from London, use M1 and M25—parking is free.

Your imagination can take you back to AD 130 as you walk around the ruins of this 2,000-seat Roman Theater, one of the few in the country. Next to the theater are the scant ruins of a Roman town house, shops, and a shrine.

From 1906 to his death in 1950, the famed Irish playwright George Bernard Shaw lived in the small village of Ayot St. Lawrence, 9 miles northeast of St. Albans. Today, his small Edwardian home, Shaw's Corner, remains much as he left it. The most delightful curiosity is his little writing hut, which is in the garden and which can be turned to face the sun.

Medieval pilgrims came from far and wide to the hilltop St. Albans Cathedral to honor its patron saint, a Roman soldier turned Christian martyr. His red-canopied shrine beyond the choir has a rare loft from where guards kept watch over gifts that were left. Construction of the mainly Norman cathedral began in the early 11th century, but the nearly 300-foot-long nave dates from 1235; the pillars are decorated with 13th- and 14th-century paintings. The tower is even more historic and contains bricks from ancient Roman buildings. Join a free tour of the highlights daily at 1:05 pm, or come for the more extensive free tours at 11:30 and 2:30 on weekdays, 11:30 and 2 on Saturday, and 2:30 on Sunday. Tower tours take place on selected dates, mostly on Saturdays. Call or check the website for the schedule.

With exhibits on everything from food to burial practices, the Verulamium Museum, on the site of the ancient Roman city, explores life 2,000 years ago. The re-created Roman rooms contain colorful mosaics that are some of the finest in Britain. Every second weekend of the month, "Roman soldiers" invade the museum and demonstrate the skills of the Imperial Army.

Adjacent to the Verulamium Museum, this park contains the usual—playground, wading pool, lake—and the unusual—Roman ruins that include part of the town hall and a hypocaust, or central-heating system. The hypocaust dates to AD 200 and included one of the first heated floors in Britain. Brick columns supported the floor, and hot air from a nearby fire was drawn underneath the floor to keep bathers warm.