Kongogumi was founded in 578 and it’s considered as the oldest company that has been always active since the beginning. I’m sure the people who founded this company did not write a business plan, or maybe they did and they wrote that they needed website. Right now they have a cool website, but they continue doing exactly what they started doing more than 1.000 years ago, they build temples, shrines and castles. For example, they built the Osaka castle.
The company was founded buy the Kongo family, and until the year 2006 it was still controlled by the Kongo family descendants. In 2006 they had some difficulties and they were adquired by Takamatsu corporation. Nowadays, it survives as a company inside the corporation.
The first temple built by Kongogumi is the Shitennō-ji, and you can visit it here (Walking distance Tennoji station in Osaka).

There are many temples built by Kongogumi in Takao.
I wonder which companies that we are used to nowadays will be still alife in 1.000 or 2.000 years. Construction? Energy? Telecommunications? Porn? Health? Spam?