 Like most other Nazi monumental structures, however, its construction was interrupted by the outbreak of World War II and was never finished.According to Speer himself, it was inspired not by the Circus Maximus in Rome but by the Panathenaic Stadium of Athens, which had impressed him greatly when he had visited it in 1935.Speer's stadium was a gigantic inflation of its Greco-Roman model, from which he borrowed the horseshoe configuration and the propylaeum, now transformed into a raised, pillared, temple-like structure ("Säulenvorhof") attached to the open end of the stadium by an internally pillared courtyard.