The first couple's only child, Marta, led mourners
The bodies of Polish President Lech Kaczynski and First Lady Maria Kaczynska are now lying in state in the capital, Warsaw.
Maria Kaczynska's body arrived earlier from Moscow amid emotional scenes after Saturday's plane crash in Russia that killed the couple and 94 others.
Parliament has held a special session to honour those killed in the disaster.
The first couple are to be buried on Sunday, a day after a memorial service for the victims in the Polish capital.
US President Barack Obama has said he will attend the funeral on Sunday.
A guard of honour stood to attention in the rain at Warsaw airport as the body of the first lady arrived on a military plane. President Kaczynski's remains were repatriated on Sunday.
After a brief religious ceremony, mourners took turns to kneel at Maria Kaczynska's casket and pay their respects as it stood on the tarmac.
AT THE SCENE
Adam Easton, BBC News, Warsaw
Warsaw's neo-classical white presidential palace has become the focal point of national mourning in Poland.
Crowds have gathered outside the building every day since Saturday's crash to light candles and lay flowers.
Flickering flames in red or yellow glass pots cover the road and pavement in front of the palace.
There's so many that street cleaners have to remove large swathes of them every morning leaving streaks of dried candle wax across the pavement flags.
Poles are getting on with their daily working lives now, but the people of Warsaw are still taking time in their busy days to make their way in their thousands to the palace to pay their respects.
The streets around the palace are thronged with families with pushchairs, senior citizens and teachers leading schoolchildren in single file. Some, like 26-year-old teacher Karolina Czurak, made a special 320-mile round-trip from her home in Bialystok, in north-east Poland, just to spend a few minutes outside the palace.
They included the late first couple's only child, daughter Marta, and Jaroslaw Kaczynski, identical twin of the late president.
Maria Kaczynska's coffin, draped with Poland's white-and-red flag, was then driven through the streets of Warsaw to the presidential palace.
Thousands of Poles lined the 10km (6 mile) route to the city centre, covering the hearse with flowers, then took turns to file past the coffins.
The first couple will be laid to rest on Sunday at Wawel Castle in the southern city of Krakow, according to Poland's PAP news agency.
A special session of both chambers of parliament was held on Tuesday to pay tribute to those who died in the disaster.
An investigation is ongoing into the crash; the plane clipped tree-tops as it tried to land in fog at a former air base north of Smolensk city on Saturday morning.
Russian officials say the pilots of the Soviet-built Tu-154 airliner had ignored weather warnings and repeatedly tried to land.
Polish prosecutors have stressed there is no evidence the crew were pressured by those onboard to ignore the advice.
The president and his party of senior Polish military and political officials had been due to attend a memorial for the Polish victims of a World War II massacre by Soviet secret police at Katyn, near Smolensk.
Relatives are in the Russian capital helping forensic scientists identify the bodies. Family members are being supported by Polish and Russian psychologists.
Forty-five of the victims have been identified, the Russian health minister said on Tuesday, reports AFP news agency.
Some of the bodies are so badly disfigured that DNA evidence will be needed.
President Kaczynski's body was identified on Saturday in Smolensk by brother Jaroslaw, who is a former prime minister.
Poland is in the middle of seven days of mourning over the tragedy.
President Dmitry Medvedev and Prime Minister Vladimir Putin have devoted much time to dealing with the aftermath of the crash.
The Russian president is expected to be among leaders attending Sunday's state funeral for Mr Kaczynski, who was an outspoken nationalist known for his distrust of Russia.
Moscow's handling of the tragedy has been widely appreciated in Poland, though others suggest the thaw in relations may not last, the BBC's Duncan Kennedy reports from Warsaw.
Meanwhile, Acting President Bronislaw Komorowski said he would announce on Wednesday the date of the country's presidential election, expected in May or June, reports Reuters news agency.
Mr Komorowski, who is parliamentary speaker, had been expected to run against the late president.
Opinion polls before the crash indicated Mr Komorowski, the official candidate of Prime Minister Donald Tusk's governing Civic Platform Party, would have comfortably beat Lech Kaczynski, who had become increasingly unpopular.
There is now speculation that Jaroslaw Kaczynski may step in to represent the Law and Justice party. Analysts say he may benefit from an outpouring of public sympathy following his brother's death.
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