Heritage advocates are celebrating the re-opening of a unique piece of Canterbury history.

Lyttelton's timeball will drop from its new tower overlooking the harbour this afternoon, after a $3 million restoration to repair earthquake damage.

Heritage New Zealand southern region director Sheila Watson says they have seismic-strengthened and completely rebuilt the tower from bottom up by using the original materials.

"The timeball will be dropping at 1pm every day and lit at night, with flags flying on special occasions."