Mourners, some of them too young to remember 1989's "Velvet Revolution," met at downtown Wenceslas Square, where Havel once spoke before hundreds of thousands of people expressing their outrage at the repressive communist regime.
They jangled their keys to make noise as anti-communist demonstrators did, sang the national anthem and observed a minute of silence for the playwright-turned politician, who died Sunday.
"His legacy will be that 'truth and love must prevail over lies and hatred,'" Havel's former adviser Tomas Sedlacek told the crowd, quoting Havel's revolutionary motto.
Barbora Rubova, born two years after the end of the repressive communist regime, said it was important to show her respect to the man who helped kick off the fall of the Iron Curtain and served as president of Czechoslovakia, and later the Czech Republic.
"He laid foundations of democracy for us all," she said.
A black flag flew over Prague Castle, the presidential seat, while many Czechs stood in line to have a chance to light candles to remember Havel. "Mr. President, thank you for democracy," read a note placed at the monument to the revolution in downtown Prague.
Others visited his villa to lay flowers and light candles. Josef Klik, a 67-year-old, was among the mourners.
"He is an unforgettable person who contributed to the fall of communism," Klik said. "And after that, he remained a moral authority for ordinary people."
Bells tolled from cathedrals and churches across the country at 6 p.m. Prague archbishop Dominik Duka, who spent some time with Havel in a communist prison, said Havel "knew what it meant to lose freedom, be denied dignity, what is repression and imprisonment."
"I am convinced that we all, no matter what our political or religious views are, should pay respect to him and thank him," Duka said.
The Czech government meets Monday to declare a period of official mourning and Havel's body will go on display at the Prague Castle on Wednesday, officials said.
Czech public television announced it would broadcast Havel's film version of his last play, "Leaving," his directorial debut. Czech public radio said it would play some of the favorite music of the noted rock music fan.
Klaus called Havel "the symbol of the new era of the Czech state," and Foreign Minister Karel Schwarzenberg added that Havel "returned dignity to the Czech nation."
Tributes poured in from around the world. The founder of the Polish anti-communist Solidarity movement and former president Lech Walesa called Havel "a great fighter for the freedom of nations and for democracy."
President Barack Obama praised Havel for his "peaceful resistance (that) shook the foundations of an empire, exposed the emptiness of a repressive ideology, and proved that moral leadership is more powerful than any weapon."
Havel's funeral may take place on Friday, the local CTK news agency reported. Details are being worked out by the government in coordination with Havel's family.