If you are referring to St. Mark's in Venice, Italy, the Church is dedicated to him and his relics are held there.

Both the Basilica and the Square are named for St. Mark the Evangelist.

St. Mark the Evangelist is one of the four authors of the New Testament Gospels. The city of Venice in Italy claims him as their patron saint, and his relics are said to be housed in St. Mark's Basilica in Venice. St. Mark is traditionally believed to have been a companion of St. Peter and traveled with him to preach the Gospel.

St. Mark is traditionally believed to be buried in the St. Mark's Basilica in Venice, Italy. His relics were said to have been stolen from Alexandria in the 9th century and brought to Venice.

St. Mark's Basilica was constructed in 1094, so now it should be 916 years old.