1. The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials. The wall, which stretches across northern China, was built to protect against invasions and raids. It is the longest wall in the world, measuring over 13,000 miles. The wall was built over many years, starting in the 7th century BC and continuing until the Ming dynasty in the 17th century. Today, the Great Wall of China is a popular tourist destination and a symbol of Chinese heritage and culture.

2. The Great Wall of China is open to visitors every day of the year. The opening hours vary depending on the season. Generally, the wall is open from 8 am to 5 pm in winter (November to March) and from 8 am to 6 pm in summer (April to October). The phone number for the Great Wall of China ticket office is +86 10 8118 2277.

3. There are several ways to access the Great Wall of China from Beijing. The most common way is to take a tour or hire a driver to bring you to one of the main tourist sections of the wall, such as Badaling or Mutianyu. There are also public transportation options, including the S2 train from Beijing North Railway Station to Badaling. Tickets for the Great Wall of China range in price depending on the section and time of year. Generally, tickets cost between 40-80 yuan ($6-$12 USD).