D4 Business Village Luzern, Commercial complex in Root, Switzerland.

D4 Business Village Luzern is a business complex in the Längenbold and Oberfeld areas of Root, built by Suva with buildings by Fischer Architekten of Zurich. Its first phase opened in 2003 with 22,500 square metres of office space; a six-storey building begun in 2017 and completed in 2020 closes the head of the quarter. The site offers 53,000 square metres of lettable space and houses over 100 companies, including Technopark Luzern, CSS and Adidas.

The first phase of D4, with 22,500 square metres of office space, was inaugurated in 2003; the Suva acted as client and Fischer Architekten of Zurich designed the buildings. The Längenbold station on the Zug–Luzern line opened in 2001 and was renamed Root D4 in 2004 with the launch of the S-Bahn Luzern and Stadtbahn Zug. A six-storey extension was announced in 2011, built from 2017 and completed in 2020, with CSS and Adidas as tenants.

The site's name comes from the Root D4 S-Bahn stop, renamed in 2004 when the Zug and Lucerne suburban rail networks launched; the station itself opened in 2001 as Bahnhof Längenbold. The Technopark Luzern, housed in the D4, serves as a start-up base for young companies. Leisure tenants such as the Pilatus Indoor climbing hall, a fitness centre and a massage and physio studio sit alongside the offices.

The site has a direct train connection and is easy to reach via motorway, making it simple to travel to nearby cities. The location makes it practical to walk between different parts of the complex or arrive by public transport.

The site offers flexible office solutions called Office a la carte, where businesses can rent spaces from hourly periods to several months. This flexibility serves startups and small firms with changing space needs.