St. Magnus Cathedral is a medieval cathedral of red sandstone, located in the centre of Kirkwall. The cathedral was begun in 1137 by Earl Ragnvald-Kali, the nephew of Earl (later Saint) Magnus. The earliest parts of the cathedral are built in ponderous Romanesque style, with later additions maintaining much of the earlier motif, but adding in early Gothic architectural detail. The vaulting of the nave is particularly fine. The cathedral is built on a 't' plan, with an aisled nave, crossing, and choir, with a central tower above the crossing.