The Mansion on O Street is an American luxury boutique hotel in the Dupont Circle historic district of Washington D.C.

The hotel is noted for eccentric interior styling which includes hidden doors, secret passages, and rooms in which all furnishings and fixtures are for sale.

The four-story building contains guest rooms, a private Social club, the O Street Museum Foundation and a conference center.

After renovations were completed, Leonards designed and built a new brownstone on the adjacent vacant lot at 2022 O Street.

The unique decor has been chronicled in books including Four Blind Mice by James Patterson, Afterburn by Zane,[5] How to Murder Your Life by Cat Marnell, and in the young adult novel Gilda Joyce: The Dead Drop by Jennifer Allison.

The hotel subsequently developed a reputation for privacy, exclusivity and a high-profile clientele[7] that has included authors, artists, musicians[8] Ambassadors[4] Presidents, and civil rights heroine Rosa Parks.