Religious and secular leaders in Jerusalem are expecting a sea of people crowding the Old City this month. Palm Sunday falls on April 9, marking the beginning of the Christian Holy Week culminating with Easter, when Christians around the world celebrate the death and resurrection of Jesus. This year, Catholics and Protestants, as well as Eastern Orthodox churches, agree to celebrate Easter on the same day.

Calculating Easter is complicated. In 325 C.E., the Council of Nicaea, a gathering of Christian bishops, decided that the remembrance of the resurrection of Jesus would be held the first Sunday after the first full moon occurring on or after the vernal equinox. The date for the vernal equinox was based on the ecclesiastical approximation of March 21. If the full moon falls on a Sunday, Easter is delayed a week. When the calendar was adjusted during the reign of Pope Gregory XIII in 1582, Eastern Orthodox churches continued to go by the Julian calendar. Now, every few years, Easter falls on the same day in both, and in 2017, all Christians will celebrate Easter on April 16.

Issa Musleh, the spokesman of the Orthodox Patriarchate in Jerusalem, said that the Old City of Jerusalem will be even more crowded for another reason. He told Al-Monitor, “For the first time in 200 years, the three main churches — Orthodox, Franciscan and Armenian — agreed to have the holy grave refurbished.”

Musleh said that the newly renovated tomb was opened to the public in a ceremony attended by church and other leaders. “The opening on March 22 was attended by Jordanian Minister of Interior Ghaleb Zoubi representing King Abdullah; a representative of Greek Prime Minister Alexis Tsipras and a representative of Pope Francis; Palestinian Minister of Jerusalem Affairs Adnan al-Husseini; and the PLO Executive Committee member responsible for church affairs, Hanna Amireh.”