Henry of Grosmont, the Duke of Lancaster, inherited the castle from his father in 1345 and remodelled the great hall with a grander interior and roof. On his death Blanche of Lancaster inherited the castle. Blanche married John of Gaunt, the third son of Edward III; their union, and combined resources, made John the second richest man in England next to the king himself. After Blanche's death, John married Constance, who had a claim to the kingdom of Castile, and John styled himself the king of Castile and León. Kenilworth was one of the most important of his thirty or more castles in England. John began building at Kenilworth between 1373 and 1380 in a style designed to reinforce his royal claims in Iberia. John constructed a grander great hall, the Strong Tower, Saintlowe Tower, the state apartments and the new kitchen complex. He made these renovations before his nephew took over his position. When not campaigning abroad, John spent much of his time at Kenilworth and Leicester, and used Kenilworth even more after 1395 when his health began to decline. In his final years, John made extensive repairs to the whole of the castle complex.