The time of construction of the pavilion Temple in Monrepo is unknown. From Ludwig Nikolai's letters to his son Paul, it follows that in 1798 the projects of two "temples" for Monrepo were handled by Giuseppe Martinelli, but he based them on the work of Tom de Thomon. At the same time as the building was being constructed, work was carried out to improve the surrounding area: the land was cleared of boulders, trees were thinned out, and a hedge was planted. Two large fir trees were left next to the new building. One of them has survived to this day.

On the peninsula, now called Neptune Peninsula, the land was cleared of stones and a terrace was built on the side of Ludwigstein Island. The natural vegetation on the site was thinned, but some old fir trees were preserved.

Such buildings, styled after antiquity, were very common in park landscapes at the end of the 18th century. Often pavilions were made of stone, but there were also wooden structures called temples.

In the poem "The Monrepo Estate in Finland" (1804), Ludwig Nikolai mentions a "open temple" in Greek style under construction, next to which stand two old fir trees. It is likely that at the time the poem was being written, the construction was not yet completed.

Inside the building was a sculptural composition depicting the goddess Pietas with an infant in her arms, symbolizing the fulfillment of duty to the gods. For this reason, the building was originally called the Temple of Piety. Nearby, on the veranda, there was a sculpture of Neptune on a pedestal decorated with a school of dolphins.

Both Neptune and the pedestal with dolphins were acquired by Nikolai as part of a large group of antique sculptures he purchased from the architect Vincenzo Brenna. Later, the sculptural image of Neptune or Jupiter was moved inside the Temple along with the pedestal, and the pavilion began to be called the Temple of Neptune.

In a number of research works, it has been suggested that in the 1830s the design or repair of the Temple pavilion in Monrepo was carried out by A.I. Stackenschneider, but this information is not confirmed by any evidence.

On the site where the pavilion was located, shore protection works were carried out, a hedge of fir trees was planted, and on two sides of the Temple of Neptune two pine trees were planted, one of which has survived to the present day.

The building survived until 1948, but was later dismantled due to dilapidation. In 1999, with the participation of the public organization “Pro Monrepos,” the temple was restored. Unfortunately, the building completely burned down in June 2011 under unknown circumstances.

It was restored again in 2018.

Sources:

https://peterburg.center/maps/gosudarstvennyy-istoriko-arhitekturnyy-i-prirodnyy-muzey-zapovednik-park-monrepo.html

https://www.spb-guide.ru/page_20244.htm

https://wikimapia.org/5184960/ru/%D0%A5%D1%80%D0%B0%D0%BC-%D0%9D%D0%B5%D0%BF%D1%82%D1%83%D0%BD%D0%B0