The Librarians set up a “basecamp” downtown Portland and are filming at several locations this week. Their first place was at The Sentinel Hotel on 11th Ave. The hotel dates back to 1909 with a massive renovation done when it reopened in 1992 to a new glorious hotel. You can read more of the hotels history at its site sentinelhotel.com. It seems a perfect setting for The Librarians filming. They were working today on the 2nd floor which includes a Library, Billiard room, Card room and a Fireside room.
The lights outside the front of the building were aimed towards a room at the center of the 2nd floor. They were also pumping cool air into the 2nd floor windows. Because of the filming being done inside the hotel it wasnt possible to view the filming they were doing. Thanks to @theportlandblog for the location tip.