In the decades that followed, Ackerman amassed an extremely large and complete collection of science fiction, fantasy, and horror film memorabilia, which, until 2002, he maintained in an 18-room home and museum known as the "Son of Ackermansion". (The original Ackermansion where he lived from the early 1950s until the mid-1970s was at 915 S. Sherbourne Drive in Los Angeles; the site is now an apartment building.) This second house, in the Los Feliz district of Los Angeles, contained some 300,000 books and pieces of film and science-fiction memorabilia. From 1951 to 2002, Ackerman entertained some 50,000 fans at open houses - including, on one such evening, a group of 186 fans and professionals that included astronaut Buzz Aldrin. Ackerman was a board member of the Seattle Science Fiction Museum and Hall of Fame, where many items of his collection are now displayed.