Tripoli's massive Red Castle — Assaraya Alhamra — overlooks the old city and the harbour. The fortress complex dates back to Roman times, though most of what stands today was built and rebuilt during the Byzantine, Arab, Ottoman, and Italian colonial periods. From the ramparts you get one of the best views in the city: the medina's rooftops below, the harbour beyond, and the Mediterranean stretching to the horizon.
The castle houses the national museum, whose galleries trace Libya's long history from Phoenician and Greek antiquity through the Roman era, the Islamic period, and the Ottoman centuries to the modern day. The Roman collection includes mosaics, statuary, and funerary objects found at sites across the country. The ethnographic section covers traditional dress, silverwork, and household objects from across Libya's diverse regions. The museum has suffered from years of neglect and intermittent conflict since 2011 — some collections have been damaged or displaced — but the castle and at least parts of the collection remain accessible to visitors with a licensed guide.