The Great Reformed Church on Kossuth tér is the largest Protestant church in Hungary and the symbol Debrecen recognises itself by. Its twin yellow towers are visible from anywhere in the city centre, and the neoclassical facade has dominated the main square since the church was finished in 1819. The interior is austere by design — Calvinism stripped Hungarian churches of their saints and gold — but the scale of the central nave and the famous Rákóczi Bell (the largest bell in Hungary) give it real weight.
For a small admission fee you can climb the western tower for a view across the city and the surrounding plain. The church remains the seat of the Hungarian Reformed Church and is still actively used for services; the museum in the side chapel covers the building's role in 1849 and the broader history of Hungarian Calvinism.