Oak has great strength, hardness, and is very resistant to insect and fungal attack because of its high tannin content. It also has very appealing grain markings, particularly when quarter sawn. Oak planking was common on high-status Viking longships in the 9th and 10th centuries. The wood was hewn from green logs, by axe and wedge, to produce radial planks, similar to quarter-sawn timber. Wide, quarter-sawn boards of oak have been prized since the Middle Ages for use in interior paneling of prestigious buildings such as the debating chamber of the House of Commons in London and in the construction of fine furniture. Oak was used in Europe for the construction of ships, especially naval men of war, until the 19th century, and was the principal timber used in the construction of European timber-framed buildings. Today red and white oak are still commonly used for furniture making and flooring, timber frame buildings, and for veneer production. Of the North American oaks, red oak is the one of most prized for lumber. It is not good for outdoor use due to its open capillaries unless the wood is treated.