Silicon Valley is named for its role at the heart of the high-tech industry and many important tech firms have their headquarters offices here.
In many cases, tourists are not allowed to enter the campus buildings and/or walk on campus, though most HQ security guards won't mind if you stop to take a quick photo at one of the main campus signs. Be discreet and follow their rules.
1600 Amphitheatre Parkway, Mountain View, California
Google owns dozens of buildings on their Mountain View HQ campus (nicknamed, "The Googleplex"), but the central campus lawn is in front of Building #43. Visitors are invited to park in one of the visitor parking spots adjacent to that building and walk around the campus grounds, taking photos of the quirky art and colorful employee bikes.
1 Hacker Way, Menlo Park, California
Facebook's headquarters in Menlo Park has a handful of visitor parking spots near the campus entrance. Visitors are not allowed to walk on the main campus, but they are invited to walk out to the main campus sign to take photos.
1 Infinite Loop, Cupertino, California
The popular maker offers an Apple Company Store for visitors to their Cupertino headquarters. Renovated in 2015, the store is a pared down version of their retail stores, selling devices as well as Apple branded logo t-shirts, mugs, and high-end accessories that aren't available anywhere else. Note: They don't offer "Genius Bar" tech support here, you'll need to go to one of their full service stores for support appointments.
2200 Mission College Boulevard, Santa Clara, California
The Intel headquarters is home to the visitor-friendly Intel Museum, which offers a background on the company's history, technology demonstrations, interactive exhibits, and more. The museum store sells Intel branded merchandise including apparel, pens, gifts, computer devices, toys, and other items.
2145 Hamilton Avenue, San Jose, California
The eBay campus in San Jose has an eBay company store that carries eBay branded merchandise like t-shirts, caps, and mugs.
100 Winchester Circle, Los Gatos, California
The Netflix headquarters office is just off of the 85 highway at Winchester Boulevard in Los Gatos. The complex is just a short drive from Downtown Los Gatos. You can't walk around the Netflix campus, but you can stop to take a photo at the sign on Winchester Blvd.
701 1st Avenue, Sunnyvale, California
Yahoo's headquarters office is located at Matilda and 1st Avenue in Sunnyvale. The main building is adjacent to the San Francisco Bay. You can't walk around the Yahoo campus, but you can stop to take a photo at the sign on 1st Avenue.