On Shabbat, the usual worshipers came to Congregation Beth Elohim in Park Slope.

The next day, the visitors came.

As part of the New York Landmarks Conservancy’s annual Sacred Sites Open House Weekend, the century-old Brooklyn synagogue welcomed people with an interest in the synagogue’s neo-Romanesque architecture, its limestone dome and its stained-glass windows.

Cantor Joshua Breitzer, Beth Elohim music director, at left, shows a group of children some musical instruments.

Also taking part in the open house was the nearby Old First Reformed Church, which hosted the congregation for High Holy Days services in 2009 and 2010 after the synagogue’s ceiling collapsed. Beth Elohim, which just completed a $1.75 million restoration of the building’s roof, skylights and parapets, returned the favor this Easter, after a partial collapse of the church’s ceiling.