An improved architecture and method of operation for providing redundancy in programmable logic devices. Spare columns or rows of logic blocks 115 and switch boxes 140 are employed to replace columns or rows of logic blocks containing one or more defective logic blocks. Associated logic enable the device to bypass a column or row of logic blocks 115 containing one or more defective logic blocks 115 and to switch in a spare column or row of defect-free logic blocks 115 as replacement.