The monument was constructed at the highest point of Calton Hill, at above sea-level, replacing an earlier mast used to send signals to shipping in the Forth. The monument was funded by public subscription and an initial design prepared by Alexander Nasmyth. His pagoda-like design was deemed too expensive, and an alternative design in the form of an upturned telescope—an object closely associated with Nelson—was obtained from the architect Robert Burn. Building began in 1807, and was almost complete when money ran out the following year. Burn died in 1815, and it was left to Thomas Bonnar to complete the pentagonal castellated building, which forms the base to the tower, between 1814 and 1816.