Original 1st printing 17 x 22" concert poster for Mountain (featuring Leslie West and Felix Pappalardi) with Brethren and Skid Row at the Boston Tea Party (15 Lansdowne St location) in Boston, MA on 11/27-28/1970. Artist unknown, medium flat index stock poster is in absolutely gorgeous mint/near mint (A/A- to A-) condition, a STUNNING-looking late-period BTP poster with a really cool kaleidoscopic design.