An important monument of the Soviet era is the Lenin's Mausoleum, which is located on the west side of Red Square. It stands by the Kremlin wall at the height of the Senate Tower, almost exactly where the protective moat ran until the 18th century and a tram line ran from 1909–1930. Inside the mausoleum, the lavishly embalmed corpse of the Russian revolutionary leader Lenin rests in an armored glass sarcophagus. To this day, the mausoleum is open to visitors on certain days.