Mansion for sale, so why is no one buying?

Many houses in the area are empty. Opportunity for homeless and Squatters.

'Squatter' laying claim to vacant homes

A Michigan man is moving in and claiming ownership of vacant homes in foreclosure.
Realtors are unable to sell the properties and police have been unable to force him out.

Squatters Are Taking Over Las Vegas

Agnes Cleary It's very telling that the city of LV sees squatters as the problem, not homelessness.

Ownership is the state or fact of exclusive rights and control over property, which may be an object, land or real estate, or intellectual property.
Ownership involves multiple rights, collectively referred to as title, which may be separated and held by different parties.

a leasehold estate is an ownership of a temporary right to hold land or property in which a lessee or a tenant holds rights of real property by some form of title from a lessor or landlord. Although a tenant does hold rights to real property, a leasehold estate is typically considered personal property.

possession is the control of a person's intentional exercises toward a thing. In all cases, to possess something, a person must have an intention to possess it. A person may be in possession of some property. Like ownership, the possession of anything is commonly regulated by the country under property law.

Personal property is a property that is movable. In common law systems, personal property may also be called chattels or personalty.

In civil law systems, personal property is often called movable property or movables – any property that can be moved from one location to another.

The concept of possession developed from a legal system whose principal concern was to avoid civil disorder.
The general principle is that a person in possession of land or goods, even as a wrongdoer, is entitled to take action against anyone interfering with the possession unless the person interfering is able to demonstrate a superior right to do so.

Different parties may claim an interest in the property by mistake or fraud, with the claims being inconsistent of each other. For example, the party creating or transferring an interest may have a valid title, but intentionally or negligently creates several interests wholly or partially inconsistent with each other. A court resolves the dispute by adjudicating the priorities of the interests.
According to the Indian property law, it defines the ‘Transfer of property means an act by which a living person conveys property, in present or in future, to one or more other living persons, or to himself and one or more other living persons; and "to transfer property" is to perform such act.

In this section "living person includes a company or association or body of individuals, whether incorporated or not, but nothing herein contained shall affect any law for the time being in force relating to the transfer of property to or by companies, associations or bodies of individuals.

Historically, leases served many purposes, and the regulation varied according to intended purposes and the economic conditions of the time. Leaseholds, for example, were mainly granted for agriculture until the late eighteenth century and early nineteenth century, when the growth of cities made the leasehold an important form of landholding in urban areas.

The modern law of landlord and tenant in common law jurisdictions retains the influence of the common law and, particularly, the laissez-faire philosophy that dominated the law of contract and the law of property in the 19th century. With the growth of consumerism, the law of consumer protection recognized those common law principles assuming equal bargaining power between parties may cause unfairness. Consequently, reformers have emphasized the need to assess residential tenancy laws in terms of the protection they provide to tenants. Legislation to protect tenants is now common.

Squatters Rights Law and Legal Definition. A squatter's right is a legal allowance to use the property of another in the absence of an attempt by the owner to force eviction. This right may eventually be converted to the title to the property over time by Adverse Possession if recognized by state law.

If the police declare this a civil matter and won't remove the squatter, start the eviction process. Once you serve the eviction notice, you could get lucky, and the squatter might leave.
If not, you'll need to file an unlawful detainer lawsuit, which is the formal way to evict. Make sure you follow your state's laws

Squatters' rights to property