In the late 19th century, St. Alexander's was remodeled into a larger, more grandiose Neo-Renaissance church with two side towers and a higher, ornate dome.

The church was established by grateful Varsovians to commemorate Tsar Alexander I of Russia,[1] who had conferred a constitution on the autonomous Congress Kingdom of Poland after the country's 18th-century partitions.

[1] The foundation stone was laid on 15 June 1818 by Treasury Minister Jan Węgliński, standing in for an indisposed General Józef Zajączek, Namestnik of the Kingdom of Poland.

During its existence the church has witnessed a number of historic events, including the 1912 funeral service for Bolesław Prus, who died a couple of blocks away in his apartment on ulica Wilcza (Wolf Street).

[3] The 17th-century white marble statue of dead Christ by a Roman or Florentine sculptor to the left of the altar was acquired in Rome by Stanisław Herakliusz Lubomirski between 1674 and 1694, and was transferred to St. Alexander's Church in 1826.