A lantern near the main entrance door of Sewerby Hall and Gardens collapsed with a crash on Friday.
The incident happened at around 1pm and Sewerby Hall are now "investigating why this happened."
An eye witness said a lot of people were visiting the attraction at the time and were "lucky to have entered a minute before."
Marie Gascoigne, facility manager at Sewerby Hall and Gardens, said: "We are aware of an incident at about 1pm on Friday August 16 when a lantern near the main entrance door of Sewerby Hall fell to the ground.
"We are investigating why this happened, but can confirm that nobody was injured.
"All our visitors to the house used the rear entrance whilst we investigated the circumstances and cleared the entrance area.
"As a precaution, we are going to carry out a check of all similar lights on our premises, but are happy to confirm that Sewerby Hall and Gardens remain open as normal."