St. Agatha's Tower, also known as the Red Tower, is a watchtower located on the island of Malta in the town of Mellieħa. It was built by the Knights of Malta in the 17th century as a coastal defence tower, to guard against attacks by Ottoman Turks.

The tower is named after Saint Agatha, who is the patron saint of Malta, and was built on a high promontory overlooking the sea, providing a panoramic view of the surrounding area. The tower is made of local limestone and stands at a height of 110 feet. It has four levels, with a spiral staircase leading to the top, where there is a platform with cannons.

During World War II, the tower was used as a radar station by the British, and in the 1970s it was used as a police station. Today, St. Agatha's Tower is a popular tourist attraction and is open to the public, offering a glimpse into Malta's rich history and military architecture. The tower also hosts various cultural events throughout the year.