|June 1900||Foundation of Sumitomo Temporary Architecture Department|
|May 1933||Hasebe and Takekoshi independently established HASEBE-TAKEKOSHI ARCHITECTS OFFICE, funded by Sumitomo Limited Partnership Corporation|
|December 1945||Renamed as Nippon Engineering Co., Ltd. (predecessor of today’s Sumitomo Corporation).
The Trading Department was newly established after merging with all Sumitomo dealers.
|July 1950||Design Department of Nippon Engineering Co., Ltd. spun off to establish Nikken Sekkei Komu Co., Ltd.|
|July 1970||Renamed to Nikken Sekkei Ltd.|
|August 1998||Establishment of Nikken Sekkei PMC (Property Management Consulting) Office|
|March 1999||Establishment of Nikken Sekkei CM (Construction Management) Office and PM (Project Management) Office|
|February 2001||Establishment of Nikken Sekkei FMS Office|
|March 2001||Establishment of Nikken Sekkei Management Solutions, Inc. (NMS)|
|April 2003||Establishment of Nikken Sekkei Value Management Office|
|January 2004||Establishment of Nikken Sekkei Value Management/Engineering Department. Unification of Tokyo and Osaka.|
|January 2005||Establishment of Nikken Sekkei Construction Management, Inc.|
|December 2019||Licensed Real Estate Brokerage (Governor of Tokyo（1）#104228)|
|July 2021||Establishment of Kyushu Branch|