Washington, D.C. is the capital of the United States and is a city rich in history and culture. If you're planning to visit, here's some essential information you'll need to know:

1. Getting there: Washington, D.C. is accessible by plane, train, and car. The city has three major airports: Ronald Reagan Washington National Airport (DCA), Washington Dulles International Airport (IAD), and Baltimore/Washington International Thurgood Marshall Airport (BWI). There are also several Amtrak train stations in the city, as well as bus and metro options.
2. Weather: Washington, D.C. experiences four distinct seasons. Summers can be hot and humid, with average temperatures in the mid-80s (Fahrenheit) and high humidity. Winters can be cold, with average temperatures in the 30s and occasional snowfall.
3. Accommodation: There are many hotels and lodging options in the city, ranging from budget to luxury. It's recommended to book your accommodation in advance to ensure availability and better rates.
4. Must-see attractions: Washington, D.C. is home to many historic and cultural landmarks, including the National Mall, which is a large park area that includes many famous monuments and memorials such as the Washington Monument, Lincoln Memorial, and Jefferson Memorial. The Smithsonian museums, which are free to the public, are also a must-visit. The White House, the U.S. Capitol Building, and the National Archives are also popular sites to see.
5. Food: Washington, D.C. is known for its diverse and vibrant food scene, with a mix of international cuisine and local specialties. Some popular local dishes include half-smokes (a type of sausage), chili, and crab cakes. There are also plenty of options for vegetarian and vegan dining.
6. Transportation: The city's metro system is a convenient way to get around, with six metro lines serving the city and its surrounding suburbs. There are also plenty of taxis and ride-sharing services available.
7. Safety: While Washington, D.C. is a generally safe city, it's always a good idea to take precautions when traveling. Be aware of your surroundings and avoid walking alone at night in unfamiliar areas.
8. Etiquette: The city is home to many government buildings and institutions, so it's important to be respectful and follow any rules or regulations when visiting these areas. Dress appropriately for each location, and be aware of any security measures in place.
9. Events: Washington, D.C. hosts a variety of festivals and events throughout the year, including the National Cherry Blossom Festival, Fourth of July celebrations, and the Smithsonian Folklife Festival. Check the city's events calendar before your visit to see what's happening during your stay.
10. Tipping: It's customary to tip in restaurants and bars, usually around 15-20% of the total bill. Tipping is also common for other services such as taxi rides and hotel staff.
11. Free Tours: Many of the city's top attractions offer free tours, such as the U.S. Capitol and the Library of Congress. It's a great way to learn more about the history and significance of these landmarks.
12. National Mall: The National Mall is a large open park area in the heart of the city, and it's a popular spot for picnics, walking, and sightseeing. Be sure to wear comfortable shoes and bring plenty of water and sunscreen if you plan to spend the day exploring.
13. Monuments and Memorials: There are many iconic monuments and memorials in the city, including the Lincoln Memorial, the Vietnam Veterans Memorial, and the Franklin Delano Roosevelt Memorial. Consider visiting them at night when they're illuminated for a different and memorable experience.
14. Museums: The Smithsonian museums are a must-see attraction, and there are over 20 of them in the city, each with a unique collection of art, history, science, and culture. Some popular ones include the National Museum of Natural History, the National Museum of American History, and the National Air and Space Museum.
15. Neighborhoods: Washington, D.C. has many vibrant neighborhoods to explore, each with their own distinct character and charm. Some popular ones include Georgetown, Dupont Circle, and Capitol Hill.
16. Sports: The city is home to several professional sports teams, including the Washington Nationals (baseball), the Washington Football Team (football), and the Washington Wizards (basketball). If you're a sports fan, consider catching a game during your visit.
17. Day trips: If you have some extra time, consider taking a day trip to nearby attractions, such as Mount Vernon (George Washington's estate), Annapolis (Maryland's capital city), or Gettysburg National Military Park (site of the famous Civil War battle).
18. Cherry Blossom Festival: The National Cherry Blossom Festival takes place in the spring and celebrates the blooming of the cherry trees around the Tidal Basin. It's a popular event, so be sure to book your accommodation in advance if you plan to attend.
19. Security: The city has a significant police presence due to its role as the capital of the United States, but it's still important to be aware of your surroundings and take precautions to keep yourself and your belongings safe.
20. Currency: The United States uses the U.S. dollar as its currency, and credit cards are widely accepted. It's a good idea to have some cash on hand for small purchases and tips.

National Harbor

National Harbor is a waterfront destination located just outside of Washington, D.C. on the banks of the Potomac River. Here's what you need to know before visiting:

1. Attractions: National Harbor is home to a variety of attractions, including the Capital Wheel, a 180-foot Ferris wheel with views of the Potomac River and the Washington, D.C. skyline. There are also several museums, art galleries, and performance venues, as well as plenty of shopping and dining options.
2. Accommodation: There are several hotels and lodging options in National Harbor, ranging from budget to luxury. Many of the hotels offer views of the Potomac River and are within walking distance of the attractions.
3. Transportation: National Harbor is accessible by car, bus, and water taxi. There are also several parking garages in the area for those driving. The National Harbor Circulator bus is a free shuttle service that makes stops at popular attractions.
4. Dining: National Harbor has a wide variety of dining options, including seafood, steak, Italian, Mexican, and Asian cuisine. Some popular restaurants include Grace's Mandarin, Bond 45, and the Walrus Oyster & Ale House.
5. Entertainment: There's always something going on at National Harbor, from live music and theater performances to outdoor movie screenings and holiday events. Check the events calendar before your visit to see what's happening.
6. Shopping: National Harbor has several retail outlets and boutique shops, including Tanger Outlets and the Peeps & Company store. There's also a farmers market that operates on Saturdays during the warmer months.
7. Waterfront activities: The Potomac River offers plenty of activities for visitors, including boat tours, kayaking, and paddleboarding. There's also a public pier for fishing and crabbing.
8. Convention center: The Gaylord National Resort & Convention Center is a large conference center located in National Harbor, and it hosts a variety of events throughout the year.
9. Nightlife: National Harbor has a lively nightlife scene, with several bars and clubs that offer live music and entertainment. MGM National Harbor is a casino and resort that also features restaurants and a theater for shows and concerts.
10. Safety: National Harbor is generally a safe destination, but it's always important to be aware of your surroundings and take precautions to keep yourself and your belongings safe. Be aware of any signs of suspicious behavior and report them to the authorities if necessary.
11. Capital Wheel: The Capital Wheel is one of the most popular attractions at National Harbor. It's a 180-foot-tall Ferris wheel that offers panoramic views of the Potomac River and the D.C. skyline. You can ride the wheel during the day or at night when it's illuminated with colorful lights.
12. MGM National Harbor: The MGM National Harbor is a hotel and casino located at National Harbor. It features a variety of dining options, a spa, a theater for shows and concerts, and a large gaming floor with slot machines and table games. Even if you're not a gambler, it's worth checking out the MGM National Harbor for its impressive architecture and art collection.
13. Events: National Harbor hosts a variety of events throughout the year, including the National Harbor Wine & Food Festival, the Cherry Blossom Beer & Wine Festival, and the National Harbor 4th of July celebration. Check the events calendar before your visit to see what's happening.
14. The Awakening Sculpture: The Awakening is a 70-foot sculpture of a giant emerging from the earth, and it's one of the most photographed attractions at National Harbor. The sculpture was originally located at Hains Point in D.C., but it was moved to National Harbor in 2008.
15. Transportation: National Harbor is located about 10 miles south of Washington, D.C., and it's easily accessible by car, bus, and water taxi. The National Harbor Circulator is a free shuttle bus that makes stops at popular attractions, and there's also a water taxi that provides service to Old Town Alexandria and Georgetown in D.C.
16. Outlets: If you're looking to do some shopping, National Harbor is home to the Tanger Outlets, which features more than 85 designer and brand-name stores. The outlets are open seven days a week.
17. Public art: National Harbor is home to several pieces of public art, including sculptures, murals, and installations. Be sure to take a walk around the area to discover these works of art.
18. Gaylord National Resort & Convention Center: The Gaylord National Resort & Convention Center is a large conference center located at National Harbor. It features a variety of dining options, a spa, and a large atrium with a fountain and tropical plants. Even if you're not attending a conference, it's worth checking out for its impressive architecture.
19. Water sports: The Potomac River offers plenty of opportunities for water sports, including kayaking, paddleboarding, and jet skiing. There are several rental companies located at National Harbor that offer equipment and guided tours.
20. Safety: National Harbor is generally a safe destination, but it's important to be aware of your surroundings and take precautions to keep yourself and your belongings safe. Stay in well-lit and populated areas, and be aware of any signs of suspicious behavior.