Kongo Gumi is the oldest continually operational business company in the world. What type of business have they conducted for over 1400 years?

...founded in 578 A.D., making it the world's oldest company. The company mainly works on the design, construction, restoration, and repair of shrines, temples, castles, and cultural heritage buildings. While Kongo Gumi traditionally specialized in traditional architecture, increased competitions from major construction companies due to the growing use of concrete in shrines and temples resulted in the company becoming a subsidiary of the Takamatsu Construction Group in January 2006.