Nanshan Xinyi A21 (Chinese: 南山信義A21), is an approved, 232.6 m (763 ft), 43-storey skyscraper office building located in Xinyi Planning District, Xinyi District, Taipei, Taiwan. With a total floor area of 141,359 m² (1,521,580 sq ft), the building is expected to be completed in 2028.^[1] The building will become the sixth tallest building in Taipei upon completion.^[2]

The building will occupy the former site of Taipei World Trade Center (TWTC) Exhibition Hall 3. It was first entrusted by the International Trade Bureau to the Foreign Trade Association to operate it until the end of 2019. After the lease expired, the National Property Administration decided to release the land, and in March 2020, Nanshan Life Insurance paid NT$31.2 billion. Winning the bid, the original plan was to build a complex commercial building with 35 floors above the ground and 3 floors underground, with a height of 202 meters. He said that the idea was to use a crystal shape. Due to the large size of the building, when viewed from the City Hall Square, it will look like Taipei 101 is completely covered, and some committee members pointed out that the design of this building feels like an axe is going to chop off Taipei 101.^[3] They think that the design does not take into account the cultural and spiritual aspects, and the glass curtain design of the building may have serious reflections. The issue of light pollution has been blocked by both the metropolitan inspection and the environmental impact assessment.^[4][5]

• List of tallest buildings in Taiwan
• List of tallest buildings in Taipei
• Xinyi Planning District