After the destruction of the First Temple, Jews believed that God would forgive them and enable them to rebuild the Temple – an event that actually occurred within three generations. After the destruction of the Second Temple, Jews wondered whether this would happen again. When the Emperor Hadrian threatened to rebuild Jerusalem as a pagan city dedicated to Jupiter, in 132, Aelia Capitolina, some of the leading sages of the Sanhedrin supported a rebellion led by Simon Bar Kosiba (later known as Bar Kokhba), who established a short-lived independent state that was conquered by the Romans in 135. With this defeat, Jews’ hopes that the Temple would be rebuilt were crushed. Nonetheless, belief in a Third Temple remains a Cornerstone of Jewish belief.
– Pharisees, Wikipedia