Directly opposite the Mausoleum, on the eastern side of the square, lies the building which houses Russia's most famous shopping mall - the State Department Store, GUM. Since the fall of communism, several other shopping centers and hypermarkets have sprung up to rival it in prestige, but GUM retains its status as a consumer Mecca for visitors to Moscow. In the Soviet Union, the top floor was home to Section 100, a secret clothing store only open to the highest echelons of the party. Nowadays the rows of exclusive boutiques are accessible to anyone with a platinum card. That said, the building itself is glorious, and there are still a few more interesting relics of a bygone era on the higher floors that make it well worth exploring.  The site has been used for trading throughout history. By 1520 there was already a large stone arcade standing here. Fire destroyed the old Upper Trading Rows, as they became known, and the current building was completed in 1893. A joint project between architect Aleksander Pomerantsev and engineer Vladimir Shukov, its steel framework and glass roof were, at the time, on the cutting edge of technology, and give GUM a certain resemblance to a large European station. It has an area to match and, at the end of the 19^th Century, it was the largest shopping center in Europe. Before the 1917 Revolution it contained a staggering 1,200 stores.  In 1928, GUM was closed by Stalin, who decided to use the building as the headquarters for officials working on the first Five Year Plan. GUM was reopened in 1953, and became one of the most popular sites for the legendary Soviet queues, which could at times extend all the way across Red Square. After privatization in the early 90s, it rapidly became the address of choice for top-end Western retailers. Journalists and travel writers often comment on the sharp contrast between prices in GUM and poverty in Russia - as if the majority of New Yorkers get their clothes from Saks, or the average Londoner could afford to do their grocery shopping in Harrods. Even if you don't intend to buy anything, a tour of Red Square should always include a quick stroll down the aisles of GUM.