From A Wiki of Ice and Fire
Ten Towers is the seat of House Harlaw. The newest castle in the Iron Islands, it more closely resembles ten castles smashed together. The castle was built by Lord Theomore Harlaw. He raised the castle after he found the ancient seat of House Harlaw, Harlaw Hall, too damp and flooded after losing three sons. There is good fishing off the Long Stone Quay.
The Main Hall
The main hall is the location of the high seat of House Harlaw. Above the seat, two giant scythes of beaten silver crossed hang.
The Widow's Tower
It is so called due to the presence of Lord Rodrik Harlaw's sister, Lady Gwynesse Harlaw, who came back to Ten Towers after the death of her husband and stayed for the rest of her life, grieving her loss.
The Book Tower
The Book Tower is the fattest of the ten towers. It is octagonal and made of large block stones.