Over 250,000 people are expected to attend the Sea Odyssey event, a weekend-long street theatre production inspired by the sinking of the Titanic.
A 30ft (9m) wooden marionette of a girl, complete with papier-mâché puppet dog Xolo, has moved from the King's Dock through the city centre, while a 50ft (15m) puppet of her uncle is making the journey from Stanley Park to St George's Hall.
Claire McColgan, Liverpool city council director of culture, told the BBC: "We've never done anything on this scale before, not even in European Capital of Culture Year. There are some incredible things which are going to happen which are a secret and I can't say yet.
"This city loves great events. People have really got into the whole story and it's made everyone smile. It's great that the whole city has come together in this spirit of imagination."
The two giants, created by French company Royal de Luxe, are made from poplar, lime wood and steel, have eyes made from street lights and hair made from horse hair.
A special team of 110 puppeteers and crane operators move the giants, who have previously visited Nantes, Berlin, Santiago in Chile and Guadalajara in Mexico.
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Photo gallery - the giant puppets in Liverpool: