Above the wrought-iron screen of the chapel there is a stained-glass window by Arnao de Flandes depicting The Washing of the Feet, which dates from 1555, while the inside of the chapel is illuminated by another stained-glass window with the hatchment of cardinal Illundain.
In the centre of chapel there is a reredos framed by pilasters in the form of inverted truncated pyramids. It probably dates from the second half of the 18C and its main shrine has a sculpture of Christ Crucified from the end of the 16C.
The side sections include paintings of the same period as the reredos. They are of little worth and represent The Virgin, St John, Two Passion Angels, and The Heavenly Father at the top.
The predella of the reredos has a sculpture of The Virgin of Los Dolores, after whom the chapel is named and who is dressed for the processions. The sculpture was made by Pedro de Mena around 1680
On the left-hand wall of this chapel there is the marble sepulchre of Cardinal Don Marcelo Spinola y Maestre by the sculptor Joaquin Bilbao who finished it in 1912.
The playing figure of the Cardinal is seen against a relief in the background representing La Inmaculada.
On this wall there interesting paintings, such as Jacob blessing his Children, a 17C Flemish painting ascribed to Pieter Van Lint, St Peter`s Denial, by an anonymous, possibly French, disciple of Caravaggio, and The Burial of Christ, which is also anonymous and of the Roman school from around 1620.
On the wall facing the altar there is a 17C painting of the Ecce Homo, and a carving representing The Kiss of Judas and the Ecce Homo together, which dates from the 16C.
Above these paintings there is a magnificent Betrothal of the Virigin to St Joseph by Valdés Leal dating from 1657.