Which opera, if any,  Venus and Adonis or Bluebeard's Castle has more acts ?
Venus and Adonis (opera) Venus and Adonis is an opera in three acts and a prologue by the English Baroque composer John Blow, composed in about 1683. It was written for the court of King Charles II at either London or Windsor. It is considered by some to be either a semi-opera or a masque, but "The New Grove" names it as the earliest known English opera.
Radamisto (Handel) Radamisto (HWV 12) is an opera seria in three acts by George Frideric Handel to an Italian libretto by Nicola Francesco Haym, based on "L'amor tirannico, o Zenobia" by Domenico Lalli and "Zenobia" by Matteo Noris. It was Handel's first opera for the Royal Academy of Music. The opera's plot is loosely based on incidents from Tacitus's "Annals of Imperial Rome".