The cycle is a work of extraordinary scale. Perhaps the most outstanding facet of the monumental work is its sheer length: a full performance of the cycle takes place over four nights at the opera, with a total playing time of about 15 hours, depending on the conductor's pacing. The first and shortest work, "Das Rheingold", has no interval and is one continuous piece of music typically lasting around two and a half hours, while the final and longest, "Götterdämmerung", takes up to five hours, excluding intervals. The cycle is modelled after ancient Greek dramas that were presented as three tragedies and one satyr play. The "Ring" proper begins with "Die Walküre" and ends with "Götterdämmerung", with "Rheingold" as a prelude. Wagner called "Das Rheingold" a "Vorabend" or "Preliminary Evening", and "Die Walküre", "Siegfried" and "Götterdämmerung" were subtitled First Day, Second Day and Third Day, respectively, of the trilogy proper.