The "Echo" Grotto with an underground passage is a complex of structures located on the territory of the Gatchina Museum-Reserve. The grotto is situated on the shore of Silver Lake in the Palace Park, and the underground passage connects the grotto with the cellars of the Great Gatchina Palace. The underground gallery is unique among all palace and park ensembles in the suburbs of Saint Petersburg. The entire complex was created in the 1770s by the architect Rinaldi simultaneously with the construction of the palace for the then owner of Gatchina, Prince Orlov.

This architectural whim, conceived for entertainment purposes, was built according to the principles of classicism and received its name due to the acoustic features of the structure: the underground tunnel is characterized by a pronounced echo effect. The underground passage, which was accessible through the cellars from the ceremonial halls and private chambers of the palace’s central building, has since the 19th century also been associated with another owner of Gatchina, Emperor Paul I, who supposedly envisaged the possibility of escaping through it from the palace in case of a threat to his life.

In the 1770s, simultaneously with the construction of the Great Gatchina Palace, an underground passage was arranged from its cellars to the western shore of Silver Lake, ending in a grotto. At that time, Gatchina belonged to the Most Serene Prince Orlov, and the project of the palace and the creator of the underground passage with the grotto was the Italian architect Antonio Rinaldi.

A structure like the grotto was a miniature "architectural whim," typical for a romantic landscape park. At the same time, the idea and appearance of the underground passage and grotto, as well as the palace itself, could to some extent be connected with the fascination with English architecture, which was widespread at the time of the palace’s construction in Gatchina. While regular parks and the Baroque era were characterized by interpreting the grotto as a monumental or park pavilion decorated with columns, sculptures, and sea shells (such 18th-century monuments as the "Grotto" of the Summer Garden, the pavilion of the same name in the Catherine Park of Tsarskoye Selo, or a similar structure in the Kuskovo estate in Moscow), the grottos of the classicism era were located in secluded spots of landscape parks and distinguished by their deliberately natural appearance.

The entire complex of the underground passage with the grotto in Gatchina was created for entertainment purposes. It plays on the echo effect: the sounds of footsteps and spoken words are repeatedly echoed in the tunnel, which is why the grotto—the exit from it—received its corresponding name. There is an opinion that the structure could thus be considered an illustration of the myth of the nymph Echo. Acoustic effects were generally used in palace construction, garden and park art, and in the creation of park buildings.

It is possible that practical considerations of usefulness for the palace owner in case of a threat to his life were still taken into account when creating the underground passage. The fate of Emperor Peter III, whose death, according to one version, was violent and involved the brother of Grigory Orlov, Alexey, might have played a certain role here. In one of the rooms on the second floor of the Great Gatchina Palace, two secret doors led to a narrow dark spiral staircase (one door led directly to the staircase, the other to a dark anteroom, from which there was also access to the staircase). During Orlov’s time, this was, according to Makarov’s assumption, the prince’s bedroom. Later, this room was turned into the Ceremonial Bedroom, and the doors ended up in its alcove. The staircase could have been used by servants. It led to the first floor, where later Paul I’s private rooms were located (the staircase could be reached from the Emperor’s Toilet), and then to the palace cellars, where the door to the underground passage was located.

For Grand Duke Paul Petrovich himself, who became the owner of Gatchina after Orlov’s death, the "underground passage is very characteristic," according to V.K. Makarov, "with his love for everything mysterious and at the same time fear of a secret enemy preparing for him the fate of Peter III." Already in the 19th century, the appearance of certain dungeons in the palace began to be attributed specifically to Paul’s time. In 1854, the lady-in-waiting Tyutcheva wrote in her diary about the "Echo" grotto: "They say that here is the exit from those underground passages that Emperor Paul ordered to be made from his room to have the opportunity to flee from assassins."

Paul could use the tunnel to Silver Lake to suddenly disappear from the palace and reappear. A wooden pier was arranged on the lake shore near the grotto, where a boat was moored and a servant waited. In 1797, the Gatchina Palace—and probably the underground passage—was inspected by the former Polish king Stanisław August Poniatowski, who was accompanied by Meshkov-Pleshcheev at Paul’s request.

After Paul I’s death, the underground passage, according to some assumptions, was closed for a long time. In 1848, a round stone pier was built at the "Echo" grotto on the site of the old wooden pier according to the project of architect E. Timm. In 1884, the platform near the grotto was repaired. During the residence of Alexander III’s family in Gatchina, the underground passage was used for the royal family’s recreational walks with children from the "Echo" to the palace.

There is an opinion that on November 1 (14), 1917, it was with the help of the underground passage leading to the "Echo" grotto that the Minister-Chairman of the overthrown Provisional Government, Kerensky, escaped from the Gatchina Palace. After the failure of the offensive by units of the 3rd Cavalry Corps on revolutionary Petrograd, he faced the danger of capture by representatives of the Soviet troops led by Dybenko, who arrived in Gatchina to negotiate with the Cossacks of the 3rd Corps. Kerensky wrote in his 1920 article titled "Gatchina," published in the French magazine "La Revue hebdomadaire," that he was aware of the existence of the underground passage:

"It is impossible to leave the palace—the building, constructed by Paul I in the form of a closed rectangle, had only one exit, already occupied by a mixed guard of Cossacks and sailors. While we were pondering how to get out of this dead end, how to escape this trap, one of the palace’s senior officials appeared with an offer of help. By his official duties, he knows a secret underground passage unknown to anyone, which leads to the park beyond the walls of this palace-fortress. But to reach this hiding place, we must wait for dusk. Well!? If nothing happens until then, we will leave the trap by this mysterious way."

According to Kerensky’s memoirs, published much later, he left the palace during the day on November 1, disguised as a sailor and passing through a crowd of armed people demonstrating in front of the building. However, in the 1920 article, he also mentioned the underground passage, claiming that "his companions," who remained in the former royal residence, all escaped: "Some simply in the confusion, others by the secret passage—all left safely from the overly hospitable palace…".

After the opening of the museum in Gatchina in 1918, the tunnel and grotto, according to some reports, were accessible to visitors. During the Great Patriotic War, the structure was practically undamaged. In the post-war period, the grotto became inaccessible for viewing, and the space of the underground passage was used as a warehouse by the city trust "Vodokanal" of Gatchina. In 1993, thanks to the efforts of the Palace LLC, the underground passage was cleared, and museum visitors were allowed inside. However, a through passage to the lake shore and viewing of the grotto remain impossible—the entrance to the tunnel from the "Echo" grotto side is closed by an arched iron door (previously it was locked with an iron grille), as Silver Lake is still used as a water supply source by the local municipal enterprise "Vodokanal," and a sanitary zone closed to park visitors is established around the lake.

The "Echo" grotto is located on the slope of a hill by the shore of Silver Lake in the Palace Park of Gatchina. Nearby on the shore are the remains of a semicircular stone pier. The grotto is designed as a kind of cave framed by dense overhanging vegetation. At its depth, below the level of the shore platform, there is an arched entrance to the underground chamber. The total length of the building’s facade is 19 meters.

The grotto’s facade is made of large, roughly hewn blocks of porous tuff of various sizes and shapes, with some chips. They are matched to each other by contours and fixed with iron ties hidden in the masonry. Thanks to the artistically thought-out selection of blocks, the entire structure is perceived as a grotto of natural origin. The surface features of the stones combined with deep seams between them create a play of light and shadow. The building has a deliberately gloomy and mysterious appearance.

The underground passage between the grotto and the palace cellars is unique among all palace and park ensembles in the suburbs of Saint Petersburg. The length of the underground passage is reported as 120 meters according to some sources, and 130 or 135 meters according to others; the width of the passage is 3.6 meters. It is an inclined vaulted gallery lined with stone, running at a shallow depth under the meadow that occupies the space between the palace and the lake. The tunnel is illuminated by daylight through four round light shafts, as well as by lanterns on the walls. The floor is paved with half-meter limestone slabs, and the gentle arched vault and walls are made of Pudost stone. Overall, the gallery is built according to the canons of classicism, as the horizontal rows of wall blocks are topped with a molding that simultaneously serves as the impost of the vault.

Regarding the acoustic features of the structure, the Russian scholar Ozereckovsky, who visited Gatchina in 1814, wrote:

"It is said that this underground passage was made by Prince Orlov, perhaps only so that echoes could be heard in it, which repeat up to four syllables when a human voice sounds from the iron grille standing before the lake in the underground chamber, and the iron gates facing the palace are closed, for as soon as they are opened, the echo no longer responds."

When a visitor enters the underground passage from the palace cellar side, the most impressive echo effect is achieved if the initial sound is made standing by the second pair of lanterns from the entrance. It is claimed that the echo can repeat up to 30 times. There is an opinion that since Paul’s time, there have been special interrogative phrases to which the echo of the Gatchina underground seems to respond meaningfully to the listener. Local historian A.V. Burlakov cites some of them, common nowadays: "Which flower is not afraid of frost!?" (the echo should answer: "Rose!"); "What was the name of the first woman!? — Eve!"; "Who stole the collars!? — You!"; "Who ruled us!? — Paul!".

Sources:

https://gatchinapalace.ru/park/attractions/grotto_of_echo.php

https://ru.wikipedia.org/wiki/%D0%AD%D1%85%D0%BE_(%D0%B3%D1%80%D0%BE%D1%82)