Final answer:
In the 1830s, St. Petersburg had several large urban ensembles as part of its urban plan, including the Peterhof Palace and Gardens and the Winter Palace and Palace Square.
Step-by-step explanation:
In the 1830s, St. Petersburg had several large urban ensembles as part of its urban plan. These urban ensembles were thoughtfully designed areas within the city that included architectural landmarks and important cultural institutions. One example of a large urban ensemble in St. Petersburg during this time was the Peterhof Palace and Gardens, which featured grand palaces, ornate gardens, and intricate fountains.
Another notable urban ensemble was the Winter Palace and Palace Square, which served as the official residence of the Russian monarchy and hosted important events and ceremonies. These urban ensembles, along with other architectural and cultural landmarks, contributed to the city's goal of rivaling other European capitals.