The commandment to make the pilgrimage to Jerusalem was nullified with the destruction of the Temple, as the mitzva is dependent on the ability to bring the offerings. Nevertheless, many Jews came and continue to come to Jerusalem for the festivals. The Sages tell stories of how men and women still made the pilgrimage after the destruction (Nedarim 23a; Shir Ha-shirim Rabba 4:2; Kohelet Rabba 11:1). Later, in the geonic period, R. Hai Gaon was one of those who traveled from Babylonia to Eretz Yisrael for Sukkot. In the periods of the Rishonim and Aḥaronim, many Jews living in countries near Eretz Yisrael would make the pilgrimage (Kaftor Va-feraḥ §86; Maharit 1:134).
Some poskim write that even though there is no longer an obligation to make the pilgrimage, one who goes to the area of the Temple for the festival fulfills a mitzva, as sanctity has never departed from the Temple Mount (Ḥatam Sofer; Shai Kohen, vol. 2 p. 523).
During Temple times, there was an additional mitzva to purify oneself by immersing before the festival (RH 16b), as only those who were pure were permitted to enter the Temple courtyard and eat sacrificial meat. However, now that the Temple is in ruins, we cannot offer korbanot, nor do we have the red heifer necessary to achieve purification from the impurity of corpses. Thus the obligation to purify oneself for the festival is null and void. Nevertheless, some maintain that even today one must immerse before the festival (Beit Shmuel, EH 55:10; Sho’el U-meshiv, Mahadura Telita’a 1:123). According to the majority of poskim, however, there is no obligation to immerse before the festival nowadays; those who choose to do so are acting piously. One who finds immersion difficult can fulfill this pious practice with “nine kavim” instead. This means he should stand in the shower while nine kavim (about 11 liters) of water streams down on him uninterruptedly. He should ensure that this water comes into contact with his entire body.