The Isaakievskiy Square is perhaps one of the dullest, most boring squares in St. Petersburg.
Sure you have this statue of Nicholas I, the St. Isaac Cathedral and Hotel Astoria. But apart from that it is big, grey, empty and boring.
That is also the reason why, if you can afford it, you should not stay at Hotel Astoria, but at Grand Hotel Europe in the center on a side street of the Nevsky Prospekt.