Zubarah (also spelled Zubara or Al Zubarah) sits on the northwest coast of Qatar, about 90 km from Doha. The fort you visit was built in 1938 as a police border post, but it stands next to the ruins of a much older and more significant settlement — a major 18th-century pearling and trading town that was sacked and abandoned in 1811.
The Al Zubarah Archaeological Site is a UNESCO World Heritage Site, listed in 2013. The ruins cover several square kilometers and include the outlines of streets, houses, and mosques from the town at its peak. The fort houses a small but well-organized museum with artifacts recovered from the site — pottery, pearl-diving equipment, trade goods. The fishing villages nearby are largely deserted now, which adds to the atmosphere.
It is a rewarding half-day trip from Doha, made better if you combine it with a stop at the coast to see traditional wooden dhows still moored in the shallow northern bays. You will need a car — there is no public transport to Zubarah.