The Church of All Nations, also known as the Church of the Agony or the Basilica of the Agony, is a Roman Catholic church located on Mount of Olives in Jerusalem, next to the Garden of Gethsemane. It enshrines a section of bedrock where Jesus is said to have prayed before the night of his arrest.

The chapel was built from 1919 to 1924 using funds from many different countries (hence the title). The symbols of each country are incorporated into the glass of the ceiling, each in a separate, small dome. The front of the church is a facade supported by a row of pillars. Above is a modern mosaic depicting Jesus Christ symbolically as the link between God and humanity. The bubbled-dome roof, thick pillars, and mosaic give the church a Byzantine look architecturally. The architect of the building was Antonio Barluzzi.

The current church rests on the foundations of two earlier ones - a 12th century Crusader chapel abandoned in 1345 and a 4th century Byzantine basilica, destroyed by an earthquake in 746.

The church is currently operated by the Franciscans; an open altar in the garden is used by the Anglican community on Holy Thursday.

The name "Church of All Nations" commemorates the contributions made by many countries to its construction. The flags of the nations are represented inside the little domes which give the whole a distinctly oriental tone. On the site of the present church there rose first a fourth century Byzantine church, later transformed by the Crusaders into a basilica.

The facade, enclosed by an elegant wrought iron fence, stands at the top of a flight of steps. A mass of pillars supports the great arches surrounding the atrium, while the tympanum is adorned with a modern mosaic representing Jesus as the Link between God and the Human Race. Inside, some remnants of the mosaic paving document the existence of the ancient Byzantine church. The presbytery is the part of the church which most attracts the attention, since a large fragment of the rock on which Jesus is supposed to have prayed the night before the Passion can be seen in front of the high altar. The rock is entirely surrounded by a crown of thorns in wrought iron. In the lunette in the apse is a mosaic representing Christ in Agony being Consoled by an Angel. In the side apses are other mosaic representations of episodes in Jesus' passion, such as the Kiss of Judas and the Arrest of Jesus.