From their website:

“The Lamont-Doherty Earth Observatory (LDEO) is a world-class science research institution that also plays a vital role in education. Established in 1949 as the Lamont Geological Observatory, our first Director was William Maurice “Doc” Ewing, a pioneering earth scientist. Doc started the Open House tradition, opening up the campus for one day each year to neighbors, students, the Columbia University community, and beyond. Even now, few science facilities of LDEO’s caliber and reputation open their doors to the community in this way. For over 50 years, Open House has remained one of our most important events, an exciting opportunity for adults and children of all ages to learn about our planet in fun and engaging ways!” Read More.