Lisa Bartlett discovered Lisbon on a whim after a business trip brought her to Spain. “I had taken a night train from Madrid. I didn’t know much about Portugal at all,” said Bartlett, who first visited Lisbon in 2002. “I walked out of the train station, and I was in love with it.”

Bartlett fell under the spell of the cafés, the castles and the churches, the feel of cobblestones under her feet and the sense that something ancient or amazing could be waiting for her around every corner. When she received an invitation from her cousin to return to Lisbon five years later, Bartlett jumped at the chance, looking forward to sharing her experience of the White City with her cousin’s 10-year-old daughter.

“She had a blast,” Bartlett said. “There’s a lot of exploring you can do just walking around. The castle, for example, isn’t so much a museum as it is just kind of a cool place for kids to explore.”

Visitors from the Phoenicians to the Gauls to the Romans to the Moors have fallen in love with Lisbon for more than 2,000 years, leaving the twisting alleys and secret sepulchral churches of its seven hills layered in history. American travelers love the fact that Lisbon is closer to the United States than any other European city — just a five-hour flight from Boston or New York — and a better value than most: The average nightly rate at Portugal’s hotels is the lowest in Europe, according to Hotels.com. They also love the sights and sounds and smells of the city: the taste of fresh-grilled sardines with a glass of Madeira or Port; the gleam of weathered marble on the tombs of kings; the 600,000 residents who embraced the concept of instant friendship long before Facebook.

“That first summer, people were super friendly to me,” Bartlett recalled. “No one had talked to me in Spain, but in Lisbon I would be sitting in a café having coffee, and people would just start conversations.”

Many visitors begin their exploration of the city at the riverside district of Belém, the place Vasco da Gama departed on July 8, 1497, for the voyage that carried him into the history books. The trade route to India Da Gama discovered helped launch Portugal’s Golden Age of Discovery, bringing riches and power to the nation and its king, Dom Manuel I. Manuel left his mark on Belém with two monuments: the Tower of Belém, built around 1515, and the Jerónimos Monastery, begun in 1502 and completed at the end of the 16th century The vast white monastery, built on the site where Da Gama and his men prayed before their journey, now contains the great sailor’s tomb in a vaulted chamber of stained glass and stone carvings.

Another wing of the monastery hosts the Maritime Museum, whose displays of model ships, uniforms and 15th-century navigational instruments helps put the achievements of Da Gama and his contemporaries in perspective. Nearby, the National Coach Museum has turned the former equestrian arena of the Belém Palace into a collection of coaches and carriages that would make any Cinderella swoon. Don’t even think about leaving the district without sampling pastéis de Belém, a creamy confection made using a recipe developed by the Jerónimos monks and kept secret for more than 200 years.

Portugal’s capital may be surrounded by castles and palaces, but when residents of Lisbon talk about “the castle,” they’re referring to the Castle of St. George, the medieval stone fortress that became the city’s — and the nation’s — capital after King Alfonso Henriques wrested Lisbon from the Moors in 1147. To reach the castle’s parapets and dungeons, climb the steep streets and winding alleys of the Alfama, one of the few districts of Lisbon to remain intact after the earthquake of Nov. 1, 1755. Within the Alfama are the Military Museum, with a wide-ranging collection of ancient armor and artillery; the National Tile Museum, which explains the history of Lisbon’s ubiquitous azulejos (colored tiles); and the unique House of Points, a 16th-century home bristling with shining metal spikes.

The city’s most popular tourist destination is located within the Park of the Nations, built along the waterfront for the 1998 World’s Fair. The park’s centerpiece, the Lisbon Oceanarium, is second only to the Osaka Oceanarium as the world’s largest aquarium. Take the kids for a walk through kelp forests and explore an Antarctic shelf while more than 25,000 creatures, from jellyfish to bat rays to penguins, gambol and glide behind its vast acrylic panels. For an additional $88, intrepid children can even sleep with the fishes, taking part in an all-night slumber party surrounded by sharks.

Two terrific getaway destinations are each half an hour from downtown Lisbon. The cliffside town of Cascais is the Portuguese Riviera, where surfers, sailors and sunbathers flock to the sandy stretches of Guincho Beach. And the town of Sintra, described by Lord Byron as a “glorious Eden,” shelters three palaces that once served as the summer home of the nation’s royalty — Palácio da Vila, Palácio da Pena and Palácio de Queluz — in addition to gardens, beaches and the Toy Museum, featuring more than 40,000 toys.

Before you leave, be sure to wander into one of the many clubs or taverns where a single guitarist plays fado, that distinctly Portuguese music of longing. It’s the perfect opportunity to reflect on your journey — and, in true Lisbon style, to ponder what might have been.

“There’s something called saudade that’s part of Portuguese culture,” said Jayme Simões, a spokesman for the Portuguese National Tourist Office. “It’s not exactly nostalgia, because nostalgia is a desire to return to something you knew, like your childhood or your college days. Saudade is a desire to go back to a time that never was, to fantasize or romanticize something that isn’t real. In a sense, all Portuguese imagine a mythical time of a great, happy nation that never existed. It’s a personal memory for everyone, even though it’s no memory at all.”

Info to Go

Portela de Sacavem International Airport (LIS) is 4.4 miles from the city center. Lisbon’s subway, the Metropolitano, is easy to navigate. The Lisboa Card, available from Turismo de Lisboa, allows unlimited travel for 72 hours on the metro, buses, trams and funiculars as well as trains to Sintra and Cascais. Visit www.visitlisboa.com.

Lodging

Hotel Avenida Palace
Located in Restauradores Square in the heart of Lisbon, Hotel Avenida Palace is a symbol of the city’s charm and elegance. Rua 1 Dezembro, tel 351 213 218 100. $$$$

Hotel Tivoli Lisboa
Specializes in “experience” packages for families, such as visiting a thoroughbred farm or following the Portuguese royal family’s route from Mafra to Queluz. 185 Av. da Liberdade, tel 351 21 319 8900. $$$

Novotel Lisbon
Offers packages for popular family destinations, including the nearby Lisbon Zoo. Children under 16 stay free with parents or grandparents. 1 Av. José Malhoa, tel 351 21 724 4800. $

Dining

Bom Jardim
The “King of Chickens” serves up roasted chicken, fries and a comfortable, friendly dining experience — equally popular with locals and tourists. 11 Travessa de Santo Antão, tel 351 21 342 4389. $$$

Restaurante Manifesto
Diners can view the park through a wall of glass while exploring Chef Luís Baena’s exquisite experimental cuisine. 9C Largo de Santos, tel 351 21 390 3583. $$$$

Restaurante Tavares
Chef José Avillez has earned the city’s oldest dining establishment a 2010 Michelin star with French-inspired dishes like Champagne-covered sole and tender lamb. 37 Rua da Misericórdia, tel 351 21 342 1112. $$$$