Simplify the following text for a Grade 11 native English-speaking person.
Original: He built the grandiose Domus Aurea on the site , in front of which he created an artificial lake surrounded by pavilions , gardens and porticoes .
Simplified: He built a grand palace , the Domus Aurea which had a lake , gardens , paths covered with a roof held up by columns ( porticoes ) , and large shelters ( pavilions ) to sit in .