Tata’s Lake Öreg is one of the oldest artificial lakes in Hungary. It was created before the 9th-century Magyar conquest of Hungary with the help of a dam built on Által-ér (stream).

They also used and continually enlarged it throughout the Middle Ages. Together with the surrounding marshland it defended Tata Castle, while in the water they kept fish brought here from the Danube. The shape similar to today’s Lake Öreg was formed in 1747 on the designs of the renowned hydraulic engineer Sámuel Mikoviny. The size of the lake then was 345 hectares. As part of the Esterházy estate it was used as a fish pond, but there were also water mills and a slaughterhouse built on it.

The lake, now nearly 250 hectares in size, falls under the international Ramsar Convention on the protection of the world’s most important aquatic habitats. It is the only urban lake in Europe where tens of thousands of wild geese and other migratory birds find temporary shelter in the autumn and winter months.