The Microsoft campus is the informal name of Microsoft 's corporate headquarters, located at One Microsoft Way in Redmond, Washington . Microsoft initially moved onto the grounds of the campus on February 26, 1986, weeks before the company went public on March 13. The headquarters has experienced multiple expansions since its establishment.
It is estimated to encompass over 8 million square feet (740,000 m 2 ) of office space and 30,000–40,000 employees.  Additional offices on the Eastside area of the Seattle metropolitan area are located in Bellevue and Issaquah . Building 92 on the campus contains a visitor center (with interactive exhibits) and store that are open to the public. 
Microsoft chose to move its headquarters from Bellevue to nearby Redmond in January 1985, selecting a 29-acre (12 ha) plot of land that would be developed by Wright Runstad & Company. Construction began on August 9, and Microsoft moved into the $25 million facility on February 26, 1986, several weeks before the company's initial public offering .  The move generated some concerns about increased traffic congestion on the unfinished State Route 520 freeway between Bellevue and Redmond; a new freeway interchange at Northeast 40th Street would later be built in 2000 to service the campus, after lobbying and partial funding from Microsoft. The initial campus was on a 30-acre (12 ha) lot with six buildings, and was able to accommodate 800 employees but eventually grew to 1,400 by 1988. The campus was originally leased to Microsoft from the Teachers Insurance and Annuity Association , a pension fund manager, until it was bought back in 1992. 
The first major expansion of the campus came in 1992, bringing the total amount of office space to 1.7 million square feet (160,000 m 2 ) on 260 acres (110 ha) of land. Microsoft also announced its intention to contain most of its future growth within Redmond, while retaining some offices in Downtown Bellevue and Factoria . 
In January 2006, Microsoft announced the purchase of Safeco's Redmond campus after the company had begun consolidating its offices at the Safeco Tower in Seattle's University District a year earlier.  In February 2006, Microsoft announced that it intended to expand its Redmond campus by 1,100,000 square feet (100,000 m 2 ) at a cost of $1 billion and said that this would create space for between 7,000 and 15,000 new employees over the following three years. 
In 2009, a shopping mall called "The Commons" was completed on the campus, bringing 1.4 million square feet (130,000 m 2 ) of retail space, as well as restaurants, a soccer field and pub to the West Campus. 
The Seattle Times reported in early September 2015 that Microsoft had hired architecture firm Skidmore, Owings & Merrill to begin a multibillion-dollar redesign of the Redmond campus, using an additional 1.4 million square feet (130,000 m 2 ) allowed by an agreement with the City of Redmond.  The city of Redmond had also approved a rezone in February 2015 to raise the height limit for buildings on the campus from 6 stories to 10. 
In November 2017, Microsoft announced plans to demolish 12 buildings on the older East Campus and replace them with 18 new buildings, adding 2.5 million square feet (230 × 10 3 m 2 ) to house 8,000 additional employees. The newer buildings would be arranged like an urban neighborhood, centered around a 2-acre (0.81 ha) open space with sports fields, retail space, and hiking trails. The program, scheduled to be completed by 2023, will raise the total number of buildings on the campus to 131.   
The campus is located on both sides of the State Route 520 freeway, which connects it to the cities of Bellevue and Seattle as well as the Redmond city center . Microsoft paid part of the cost for an overpass over the freeway at NE 36th Street to relieve congestion on other cross-streets in the area. 
The campus is served by buses to Seattle and some Eastside cities at the Overlake Transit Center , operated by Sound Transit and King County Metro . The RapidRide B Line also runs through the campus, connecting to downtown Bellevue and Redmond.  The transit center opened in 2002 and will be the eastern terminus of the East Link light rail extension, scheduled to open in 2023.   Microsoft partnered with Sound Transit and the City of Redmond to fund a pedestrian bridge connecting the light rail station to both sides of its campus to open in 2020, providing $33.3 million of the cost.  
For employees, Microsoft also operates a commuter bus service called "The Connector" that provides non-stop service to neighborhoods in Seattle, the Eastside, and Snohomish County from the Redmond campus.  The shuttles, which began operating in 2007, were targeted in early 2014 as a symbol of gentrification in similar fashion to the Google bus protests in San Francisco, California that same year.