All eyes are on Rio's rebuilt Maracana Stadium for the opening ceremony.
Details of the opening ceremony are always a closely-guarded secret, but what is known is that the budget for Rio's festivities is substantially lower than the £31m devoted to director Danny Boyle's London 2012 extravaganza.
Reports in 2015 suggested Rio ceremony director Fernando Meirelles - who made films like City of God and The Constant Gardener - could be working with as little as one-tenth of Boyle's budget.
Organisers told the BBC that Rio's ceremony will still be "the biggest event in the world - not just Brazilian culture but world culture".
There is no ticketed sports action outside the opening ceremony on Friday, but there is still some activity at Rio's Sambadrome. Similarly to London 2012, archery holds its behind-closed-doors ranking round to seed the competitors for the events ahead.