St. Mark's Tower or Qalet Marku is a fortification on the island of Malta built by the Knights of Malta. It is a small watchtower that stands on Qrejten Point on the north shore of Malta. St. Mark's Tower has sight of Għallis Tower to the west, and Madliena tower to the east. The tower still stands and appears to be in reasonable condition. It was one of the thirteen de Redin towers constructed during the reign of Grand Master Martin de Redin.