WASHINGTON — A funeral Mass for Justice Antonin Scalia was scheduled to be celebrated at the nation’s largest Roman Catholic church, a place where popes have prayed and millions of pilgrims and tourists have visited.

The Mass on Saturday morning at the Basilica of the National Shrine of the Immaculate Conception capped two days of official mourning for Scalia, who spent nearly three decades on the high court and was one of the country’s most influential conservatives.

The basilica can hold at least 3,500 people, and those seats were expected to be filled with family, friends and dignitaries. Members of the public could also can attend without an invitation, but they had to get there early to pass through security, basilica spokeswoman Jacquelyn Hayes said.

All the current Supreme Court justices were expected to attend. Burial plans have not been announced.

More than 3,000 people — from President Barack Obama and first lady Michelle Obama to former law clerks, locals and tourists — paid tribute to Scalia at the Supreme Court on Friday, where his flag-draped casket was set atop a funeral bier first used after President Abraham Lincoln’s assassination.