Hailong Market, Electronics marketplace in Zhongguancun, China.

Hailong Mansion is an office building at 1 Zhongguancun Street in Haidian District, Beijing, with 18 floors and a total area of 73,000 square metres. Its first to sixth floors housed the Hailong Electronics Market, while floors seven to eighteen are mostly offices.

Hailong Mansion was built on the site of the former Haidian District supply and marketing cooperative; construction began on 29 March 1998 and the building was topped out on 21 December 1998, with a total area of 73,000 square metres. Hailong Electronics Market opened on 18 December 1999, ending Zhongguancun's dominance by small electronics markets and forming the "old three" with Silicon Valley and Pacific. It closed on 7 July 2016.

The name Hailong means "sea dragon". The electronics market traded from floors 1 to 6 from its opening on 18 December 1999 until it closed on 7 July 2016, after which the upper floors continued as offices. Vendors' aggressive sales tactics became notorious enough that the market turned into a byword for swindlers.

The building sits near Zhongguancun and Haidianhuangzhuang stations on Subway Line 4, with additional bus routes nearby. The multi-story structure requires time to explore all areas thoroughly.

The building's total floor area is 73,000 square metres, 26 times that of the former Haidian District supply and marketing cooperative building it replaced on the same site. The electronics market occupied floors 1 to 6, while floors 7 to 18 were mostly offices.