This Belgian semi-postal stamp, issued in 1942, depicts the interior of the Basilica of the Sacred Heart (Basilique du Sacré-Cœur) in Koekelberg, Brussels. The massive Art Deco-style church is one of the largest basilicas in the world, symbolizing national unity and faith. The stamp was part of a fundraising issue, with a surcharge of 25 centimes to aid charitable causes during wartime. Printed in brown, the design highlights the grandeur of the basilica’s domed interior and altar. A notable item for collectors of Belgian architecture, religious themes, and semi-postals.