The architecture of the imperial residences in the suburbs of Saint Petersburg is imbued with antique motifs, but Apollo's Colonnade, without a doubt, is unparalleled in its imitation of the ancient Greek style. It is located within Pavlovsk Park, on the left bank of the Slavyanka River, and at first glance leaves anyone puzzled: it seems as if you are standing among the ruins of the Parthenon rather than in the lush undergrowth of the central Russian region.

The poet E. D. de Saint-Maur, who visited Pavlovsk in the 1820s, wrote several stanzas about the colonnade, calling it an "airy temple," whose ruins are "full of captivating vitality."

The image of the ancient god Apollo was meant to express the idea of the triumph of nature and art in the park, and Cameron built the Temple of Apollo in the spirit of ancient structures.

Apollo's Colonnade is situated opposite the Grand Palace, on the high bank of the Slavyanka, and is one of the most perfect buildings in Pavlovsk Park. In the 18th century, there was a cult of art in garden design, and at the request of Maria Feodorovna in 1787, Pavlovsk's chief architect Charles Cameron created Apollo's Colonnade, the patron of sunlight and the arts. It is made of light Pudost stone and has the form of an open, through colonnade with a double row of columns arranged in a circle. In the center, on a high pedestal, stands a statue of Apollo (the Belvedere Apollo), cast after a famous ancient model kept in one of the rooms of the Vatican Palace of the Roman Pope – the Belvedere. In ancient Greek mythology, Apollo is the god of the sun and light, the patron of the arts. In 1799, the Temple of Apollo, as the colonnade was called, was moved to the edge of the high bank of the Slavyanka, which further enhanced the resemblance of the "dwelling of Apollo" to the legendary Parnassus. The source of poetic inspiration for the inhabitants of Parnassus was considered to be the Castalian spring, whose clear waters fell to the foot of the mountain. Therefore, a cascade was built from Apollo's Colonnade, which poured down powerfully to the Slavyanka. The statue of Apollo was made by the Russian sculptor Fyodor Gordeyev. Russian craftsmen Zaitsev, Makovkin, and the stonemason Rebrov, who built the sluice for the cascade, took part in the construction. The upper part of the colonnade is decorated with medallions, bas-reliefs, and stucco in the form of laurel garlands.

Originally, the colonnade was located in an open sunny spot near the park entrance from the side of Tsarskoye Selo, but in 1800 Paul I ordered the structure to be moved closer to the palace so he could see it from his chambers.

The author of the composition, Cameron, was categorically against this decision and argued for a long time. The relocation was then entrusted to Giacomo Quarenghi. The colonnade was installed on the top of a hill symbolizing Mount Parnassus, and a cascade was also arranged, descending over stones into the river.

However, in 1817, after a thunderstorm, water undermined the foundation of the structure, and part of the columns collapsed, taking the upper part—the entablature—with them. The park caretakers made a decision in the spirit of the century—not to restore the structure, as the broken columns gave it an even more antique and romantic appearance. Previously, the building was circular in plan; now, after the natural "destruction," it turned into a semicircle, and the figure of Apollo became clearly visible from the Pavlovsk Palace.

Source: 

https://www.spb-guide.ru/page_20048.htm

https://www.citywalls.ru/house25535.html