Gazprom City, a proposed complex of stylish modern buildings that evoke, among other things, a gas-fueled flame, a strand of DNA and a lady’s high-heeled shoe, would sit on a historic site on the Neva River here, opposite the Baroque, blue-and-white Smolny Cathedral.

In any of six designs under consideration, the main tower would soar three or four times higher than this city’s most famous landmarks, an alteration of the landscape that has drawn heated protests from the director of the Hermitage Museum and the head of the local architects’ union.

But Gazprom, Russia’s state-controlled energy company, is determined to press ahead and is soon to announce the winner of an international design competition. As an arm of the Kremlin, opponents say, Gazprom usually gets its way.