When you visit the David Rumsey Map Center at Stanford University's Green Library, if you can, take the stairs. Yes, you'll have to spiral up three flights, but the wallpaper will give you plenty of excuses to take a break. Like: a Grand Canyon panorama, a birds-eye view of Manhattan, and a Buddhist world map featuring the imagined spiral of headwaters for the region's three great rivers high in the Himalayas. There are more, but don't dally too long. The stairwell is barely a prelude.

The Center itself is classroom-sized, and packed with approximately 150,000 historical cartographic artifacts. Many are stored in wooden cabinets that take up an entire wall. Along the other walls are globes galore, banquet table-sized plats, and massive, many-paneled digital touchscreens capable of calling up millions of megabytes of high-resolution historical maps stored on Stanford's servers.

This balance of classic mapping and modern cartography makes the center unique among map collections. Most of the big ones are on the east coast: Yale, Harvard, and the New York Public Library all have legendary collections. "But none of them are fully integrated map centers, with technology for modern research applications," says G. Salim Mohammed, the center's director and curator. In other words, historical maps aren't just cool to look at: They give researchers ways to measure things like land use, river systems, settlement, and climate through the centuries.

One important tool is georeferencing. See, ancient maps weren't very standardized. One cartographer might have exaggerated the size of lakes, rivers, and forests, while another the next century might have measured things more to a realistic scale. (And a whole slew of others might have thought California was an island, but more on that later.) Georeferencing, which Rumsey is an expert on, is the exacting practice of correlating points on different maps. The map center doesn't just have thousands of georeferenced maps—it has computers that can call up pairs side by side at the library.

Or, at your home. For the past 19 years, Rumsey has made his collection available on the Internet. Pushing this digitization into perpetuity is one of the reasons he chose to donate to Stanford. Four floors below the Map Center, Stanford's Green Library has a scanning center mostly dedicated to digitizing historic maps. A pair of technicians lay the pieces out on a large, flat table beneath a 60 megapixel camera1. These scans make their way onto the Stanford Digital Repository, a clearinghouse for high resolution maps.

Stanford's tech savvy library is what really drew Rumsey to the California university. For the past 19 years, Rumsey has digitized his 67,000 maps from his personal collection onto a self-sustained, public website. His digital collection will join Stanford's, and the rest of his donated physical library will eventually be scanned as well, and given a permanent URL. "This link always takes you to that map, from now until forever," says Rumsey.

But really, the best part of the Map Center is the collection of classic maps that you can spend hours poring over. With a librarian's permission, you can check out things like a Mexican cultural atlas made shortly after the country's liberation from Spain. Another shows Paris' growth through the centuries. The Center also houses the McLaughlin collection, which includes around 700 maps made during the 17th and 18th centuries that depict California as an island. It was a silly time.

The David Rumsey Map Center officially opens this evening with a reception beginning 6pm local time. The following two days will be packed with talks about topics like using maps as historical tools and using GIS technology to turn maps into stories. Henceforth, the Map Center will be open to all Monday through Friday, 1 pm to 5pm. (The morning hours are reserved for researchers, classes, and etcetera.) Visitors can apply for guest passes at the Green Library's front desk.

1 Update: 04/23/2016 10:30pm This article previously stated this camera was a mere 16 megapixels.