The forthcoming transfer of St. Isaac’s Cathedral in St. Petersburg being a UNESCO World Heritage Site to the Russian Orthodox Church ignites a heated debate within the Russian society. The cathedral being part of the State Museum Complex stands out as a pearl of the world’s iconic architecture. Furthermore, it is the second most visited museum after the Hermitage, boasts an outstanding exhibition potential, and it regularly hosts church services and ritual events. Museum collections exceed twenty-four thousand items of storage, and they continue to be replenished with found rarities and newly restored objects with the status of a relic to be protected. The aim of the article is to measure the value of the assets of the monument building, assessing the insured value of the object. Uncertainty of the future use of the disputed object, however, allows us to consider the calculation capabilities and methodical tools of valuation activities to measure the market and insurance value of such a real estate object and land plot, for example, in order to practice damage compensation and transfer the object from the balance sheet of one owner to balance of another owner. The latter circumstance determines the main discourse of this study. The present article is devoted to questions of an expert estimation of the insured value of the object of research in the form of St. Isaac’s Cathedral. The article is a continuation of a series of previously published works by the author.