We meet at the Powell Auditorium of the Cosmos Club,
2170 Florida Avenue NW, Washington DC 20008.
Entrance is through the club gate, the first right-hand entrance on Florida Avenue north of the intersection with Massachusetts Avenue NW. The auditorium entrance is to the left of the gate. The Powell Auditorium is within walking distance of the DuPont Circle Metro stop (Q Street exit), the Connecticut Avenue bus routes (L2, L4), and the Massachusetts Avenue bus routes (N2, N4).
Here is a Google Map zoomed in on the Powell Auditorium. The entrance is on the south side of this gray rectangle:
Here is a PDF directions sheet that can guide you: