An excellent DVD is out at last!
From "Anchor Bay". A digitally remastered two-disc edition with a pristine image quality and sound. The second disc is filled with extras: the making of the film, the documentary "Rome in Madrid" narrated by James Mason, Dimitri Tiomkin's music, trailers, documentaries on Ancient Rome, etc. And all for just £5 at HMV.
"El Cid" is also available from the same firm, but not "55 Days at Peking", and it doesn't seem like it will ever be. I've been waiting for years!