51°39'21.2"N 5°26'28.9"E Heeswijk Castle was built on a meander of the small River Aa. The 20th century canalized Aa now flows at some distance of the Castle. However, in the early decades of the 21st century the original bed of the Aa closer to the castle, was restored and now gets enough water. The Aa was crucial for transporting heavy goods between 's-Hertogenbosch and Helmond, and perhaps even somewhat higher upstream. This gave an economic reason to build the castle on the river. On the other hand, the Aa was a barrier for east–west movement, especially by armies. This also gave the castle a strategic position, which it would keep for centuries.