In terms of urban population, Tianjin is the fourth largest in China, after Shanghai, Beijing, and Guangzhou. In terms of administrative area population, Tianjin ranks fifth in Mainland China. The walled city of Tianjin was built in 1404. As a treaty port since 1860, Tianjin has been a major seaport and gateway to Beijing. During the Boxer Rebellion the city was the seat of the Tianjin Provisional Government. Under the Qing dynasty and the Republic of China, Tianjin became one of the largest cities in the region. At that time, numerous European-style buildings and mansions were constructed in concessions, many of which are well-preserved today. After the founding of the People's Republic of China, Tianjin suffered a depression due to the policy of the central government and 1976 Tangshan earthquake, but recovered from 1990s. Nowadays Tianjin is a dual-core city, with its main urban area (including the old city) located along the Hai River, which connects to the Yellow and Yangtze Rivers via the Grand Canal; and Binhai, an adjacent New Area urban core located east of the old city, on the coast of the Bohai Gulf. As of the end of 2010, around 285 Fortune 500 companies have set up base in Binhai. Since 2010, Tianjin's Yujiapu Financial District has become known as "China's Manhattan" and the city is considered one of the world's top 100 cities, including in the Global Financial Centres Index. Tianjin is ranked as a Beta (global second-tier) city by the Globalization and World Cities Research Network. Tianjin is also one of the top 25 cities in the world by scientific research outputs as tracked by the Nature Index and home to multiple notable institutes of higher education, including Tianjin University, Nankai University, Tianjin Medical University and Hebei University of Technology.