When arranging the Mikhailovsky Garden (1819-1826), Carlo Ivanovich Rossi partially preserved the plantings of the former formal garden, as well as two ponds – a legacy of Rastrelli from the early 1740s. The unique cast-iron bridge in the Mikhailovsky Garden was built according to Carlo Rossi’s design in 1826, replacing a wooden one that had survived from the previous formal garden layout. Rossi’s cast-iron bridge is a small openwork pontoon constructed across the channel between two ponds in the Mikhailovsky Garden. The bridge was built in the 18th century based on a design by architect Carlo Ivanovich Rossi and was restored again in 2003. The exact date of the bridge’s original appearance has not yet been established. Among all the documentation related to the pontoon, only a drawing signed by Rossi, dated 1825, was found.

A few years later, the Resurrection Canal near the southern facade of the Mikhailovsky Palace was filled in. This disrupted the water system, and the pond by the fence became shallow. Soon it was filled in, and part of the bridge ended up underground. During the reconstruction of the Mikhailovsky Garden from 2002 to 2007, works were carried out similar to those led by Rossi in the first third of the 19th century, as well as new works dictated by the conditions of the modern garden. The old large pond was cleaned of silt and the cobblestone paving of the bottom and slopes was restored. The small eastern pond, filled in 1902 during the construction of the Ethnographic Museum, was fully recreated. A great success for archaeologists was the discovery of the original supporting structures of Rossi’s cast-iron bridge, buried along with the pond. Restored, it took its historic place, hanging like openwork lace over the mirror-like surface of the waters.

When developing the restoration project, the requirement of the State Inspection for the Protection of Monuments (GIOP) to preserve all load-bearing cast-iron structural elements was taken into account.

The bridge consists of brick abutments faced with limestone blocks, five cast-iron lattice trusses (load-bearing structures) made by casting, and a cast-iron parapet railing fixed on pedestals with decorative elements.

To date, Rossi’s bridge is the only bridge structure in Saint Petersburg with original cast-iron arched structures and cast-iron elements (only a small number of them have been recast based on surviving originals).

Sources:

https://rusmuseumvrm.ru/online_resources/e-course/sady/str/str12.html