Castellvell de Solsona is an 11th-century fortress crowning an 838-meter hill in the municipality of Olius, three kilometers from Solsona in Lleida province, declared a Cultural Heritage Asset of national importance. Construction began on Count Sunyer d'Urgell's orders in 957, with reinforcement by Count Borrell II of Barcelona in 973 as a military citadel. Later strengthened by Lord Miró in the 11th century and completed by descendants Bernat and Ramon de Tarroja in 1217, the castle features an 11th-century tower with 2.16-meter interior diameter and 2.20-meter walls. Converted into a sanctuary with a Gothic-style chapel dedicated to Santa María de Castellvell, it remains inhabited and well preserved as a significant example of Catalan medieval military architecture.
