Hidden beneath a private house in Dunakeszi lies one of the most remarkable remnants of the Roman Danube limes - the ruins of a late Roman port fort dating back to the 4th century. Discovered by chance, the site now offers visitors a rare glimpse into Rome's frontier defenses through a small private museum.

The fort was part of Emperor Valentinian I's ambitious plan to control the left bank of the Danube between the territories of the Quadi and Sarmatians. Directly across the river at Horány stood a twin fort, and a ferry once crossed between them - remarkably, a modern ferry still runs almost the same route today. A 28-metre stretch of the southern wall survives, one of the best-preserved sections among known port forts of this type in Hungary. The atmosphere is intimate and authentic, as visits take place in small groups within the actual house where the ruins were found, giving a genuine sense of discovery.

• Dunakeszi, Duna sor 28 street - accessible by car or public transport from Budapest, easy access

• Visits only by prior appointment
• The private museum is located in the basement and garden of the house at Duna sor 28
• The site has been under heritage protection since 2004
• The exhibition presents the fort's history and archaeological finds from the site

Interestingly, the fort was uncovered by chance in 2002 during house construction, and the owner chose to preserve and display the ruins rather than cover them up again.