Piantou Pass for some , passing through important passes like the Pingxing Pass and Yanmen Pass before joining the Outer Great Wall at Sihaiye in Beijing's Yanqing County. The sections of the Great Wall around Beijing municipality are especially famous: they were frequently renovated and are regularly visited by tourists today. The Badaling Great Wall near Zhangjiakou is the most famous stretch of the wall, for this was the first section to be opened to the public in the People's Republic of China, as well as the showpiece stretch for foreign dignitaries. The Badaling Great Wall saw nearly 10 million visitors in 2018, and in 2019, a daily limit of 65,000 visitors was instated. South of Badaling is the Juyong Pass; when it was used by the Chinese to protect their land, this section of the wall had many guards to defend the capital Beijing. Made of stone and bricks from the hills, this portion of the Great Wall is high and wide. One of the most striking sections of the Ming Great Wall is where it climbs extremely steep slopes in Jinshanling. There it runs long, ranges from in height, and across the bottom, narrowing up to across the top. Wangjing Lou Wàngjīng Lóu) is one of Jinshanling's 67 watchtowers, above sea level. Southeast of Jinshanling is the Mutianyu Great Wall which winds along lofty, cragged mountains from the southeast to the northwest for . It is connected with Juyongguan Pass to the west and Gubeikou to the east. This section was one of the first to be renovated following the turmoil of the Cultural Revolution. At the edge of the Bohai Gulf is Shanhai Pass, considered the traditional end of the Great Wall and the "First Pass Under Heaven". The part of the wall inside Shanhai Pass that meets the sea is named the "Old Dragon Head". north of Shanhai Pass is Jiaoshan Great Wall ( Jiāoshān Chángchéng), the site of the first mountain of the Great Wall. northeast from Shanhaiguan is Jiumenkou Jiǔménkǒu), which is the only portion of the wall that was built as a bridge. In 2009, 180 km of previously unknown sections of the Ming wall concealed by hills, trenches and rivers were discovered with the help of infrared range finders and GPS devices. In March and April 2015, nine sections with a total length of more than , believed to be part of