Grimm belonged to the second generation of Russian neo-Byzantine architects and was the author of Orthodox cathedrals in Tbilisi, Chersonesos and smaller churches in Russia and Western Europe.

Rather than waiting until the end of hostilities, Grimm opted for a study tour of the Caucasus (1849–1850) that exposed him to the wealth of vernacular Georgian and Armenian architecture.

In 1858 empress Maria Alexandrovna commissioned Grimm to design the cathedral in Chersonesos, on the site of a Greek church where Vladimir I of Kiev was baptized in 988.

In 1865 Grimm and Robert Gedike jointly took part in the contest to design a new cathedral in Tbilisi but lost to Victor Schroeter and Alexander Huhn.

The client – viceroy of the Caucasus Mikhail Nikolayevich – dismissed the Schroeter-Huhn proposal as too expensive; he supported the Grimm-Gedike draft but instructed the architects to decrease its size to cut costs.