A monumental structure is something very big and impressive that's often used as a memorial or to honor someone. Think of a huge statue or a grand monument on top of a hill.
The word "monumental" is commonly used to describe things that are impressive, large, or remarkable. For example, when a famous artist creates a massive sculpture, we might say it's a monumental work of art. It's also used to talk about something that's extremely big or heavy - like a monumental task, which means a very difficult job. In some cases, people use the word "monumental" to describe an achievement or event that will be remembered for a long time. For instance, if someone breaks a world record in sports, we might say it's a monumental accomplishment.
In the manner of a monument.
