What type of interest allows one to have ownership rights of real estate that could continue forever?

Fee simple interest is the type of interest that grants the owner full and unrestricted ownership rights to real estate that can last indefinitely. This form of ownership is the most complete estate one can hold in real property, meaning that the owner can use the property, sell it, or pass it on to heirs without any limitations on duration.

In contrast, other options like life estates only grant ownership for the duration of an individual's life, after which ownership reverts to another party. Determinable fees and conditions subsequent involve certain conditions or limitations that could cause the property to revert back to the original owner or their heirs if specific criteria are not met. Therefore, fee simple interest is unique in that it provides the greatest level of ownership and security in terms of property rights that can extend indefinitely.