Natchez &8212; A Natchez landmark since its first worship service on Christmas Day 1843, St. Mary Basilica on Sunday will host the fourth meeting in a series of tours of downtown houses of worship.

The program, 4 to 5:30 p.m., will include a short worship service, a history and tour of the church, a special exhibition and refreshments in St. Theresa Hall.

The Sunday program will center on some of the high points in the evolution of the church interior design.

For several decades after the building opened for worship services, the interior remained unfinished, said the Rev. David O&8217;Connor, pastor.

&8220;Most of the stained-glass windows were installed in the 1880s,&8221; O&8217;Connor said. &8220;The exterior probably looked much as it does today in the 1840s, but the interior was a work in progress for about 40 years.&8221;

There was a gradual enhancement of the interior, from the stained glass to the statuary. &8220;It was a major milestone in the history of the church to make the inside of the building attractive,&8221; O&8217;Connor said. &8220;The formal dedication didn&8217;t come until 1882.&8221;

Another major renovation took place in the 1930s as the diocese prepared to celebrate 100 years. A few other small stained-glass windows were added, as was the handsome Carrara marble across the altar area.

Damage to the church by the straight-line winds or a tornado in early 1998 led to more repairs and renovations, including the &8220;master work on the interior,&8221; O&8217;Connor said.

From the late 1990s to June 2002, work continued, outside and inside, culminating with a complete over-haul of the lighting and sound systems.

&8220;Initially St. Mary was the cathedral for the diocese of the state,&8221; O&8217;Connor said. &8220;That means St. Mary was the bishop&8217;s number one church in Mississippi.&8221;

In 1948, the bishop decided to move to Jackson. From that time until 1977, the diocese was the Natchez-Jackson Diocese. Then in 1977, the Diocese of Biloxi was established, including 17 southern counties, and the rest of the state became the Diocese of Jackson.

Members of the St. Mary congregation began in the late 1980s to seek the basilica status for St. Mary. They succeeded. The formal designation was made in September 1999.

&8220;What it means to be a basilica is that St. Mary becomes the pope&8217;s own church,&8221; O&8217;Connor said. &8220;If he came to Mississippi, this would be his church.&8221;

Basilica is a title given for much more than the building; it involves an examination of the congregation and programs of the church, as well.

&8220;There is an examination of what type of religious education is in the congregation, Bible study, whether the children are being formed and catechized and whether the sacraments are being celebrated and understood properly,&8221; he said.

Becoming a basilica was a proud moment for the congregation, he said. &8220;There are approximately 250 dioceses in the United States but only 31 basilicas.&8221;

The Sunday program is a result of an interfaith committee at St. Mary presenting the idea of congregations of downtown churches opening on a set schedule once a month to help various denominations get to know about one another&8217;s churches and beliefs.

O&8217;Connor said he is pleased with the participation to date. In January, the program will be at Holy Family Catholic Church and, in February, at Trinity Episcopal Church.