A grotto pavilion decorated inside with seashells and tufa (porous limestone) was an invariably feature in Western European regular parks of the eighteenth century.

The project for the construction of the Grotto on the bank of the Great Pond in the Catherine Park was drawn up by the architect Rastrelli. Most of the work to construct it was carried out in 1755–56 under Empress Elizabeth, but it was completed in the 1760s under Catherine II.

Both the ground plan and the treatment of volumes – with rounded corners, niches for statues and large semicircular exedrae forming projections on the end walls – are typical of Baroque architecture. The rich opulence of the Baroque also characterizes the facades that are decorated with elaborately grouped columns supporting broken pediments. Rising above the central part of the pavilion is a dome with four lucarne windows that used to be topped by pyramidical figured pediments made of wood (the carving, produced by Okhta craftsmen, has survived and is in the stores of the museum-preserve). Masks of Neptune on the keystones of the windows, capitals with dolphins instead of volutes and figures of tritons underline the pavilion’s link to the watery element. But Rastrelli’s plan to decorate the interior of the Grotto with seashells and tufa was not implemented.

In 1771 a new project for the interior decoration of the pavilion was drawn up by the architect Antonio Rinaldi (1709–1794). The lightweight exquisitely drawn décor of the walls that was done to his designs has survived down to the present. In 1792 wrought-iron grilles embellished with ornament made of gilded sheet copper were installed on the windows and doors of the Grotto.

After it was decorated, in the 1780s, the pavilion became known as the Morning Hall. At that time, in accordance with Catherine II’s wishes, ancient sculptures and vases made of coloured stone were installed here, as well as Houdon’s statue of Voltaire that is now on display in the State Hermitage Museum.

This pavilion was glorified by the Russian poet G. Derjavin in the 18th century.

The landing-stage in front of the Grotto was reconstructed in 1830 and 1872. During the Second World War it was almost completely destroyed and it was rebuilt in granite in 1971–72 to a new design.

At present the pavilion is used as a venue for temporary exhibitions.