I would use this expression: if you offer sth you don't need to pay for it.

Palazzo, whose free use was granted by the foundation.

another option

or
complimentary use of the space was graciously granted to the Foundation by the ....
or
which was granted rent free from the...

complimentary means free of charge, while a "grant" is something provided for free by the government which reinforces the whole rent-free scenario

Dictionary.com Unabridged (v 1.1) - Cite This Source
com·pli·men·ta·ry /ˌkɒmpləˈmɛntəri, -tri/ Pronunciation Key - Show Spelled Pronunciation[kom-pluh-men-tuh-ree, -tree] Pronunciation Key - Show IPA Pronunciation adjective, noun, plural -ries.
–adjective 1. of the nature of, conveying, or expressing a compliment, often one that is politely flattering: a complimentary remark.
2. given free as a gift or courtesy: a complimentary ticket.
–noun 3. something given or supplied without charge, as lodging, transportation, or meals, esp. as an inducement to prospective customers.


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[Origin: 1620–30; compliment + -ary]

Dictionary.com Unabridged (v 1.1) - Cite This Source
grant /grænt, grɑnt/ Pronunciation Key - Show Spelled Pronunciation[grant, grahnt] Pronunciation Key - Show IPA Pronunciation
–verb (used with object) 1. to bestow or confer, esp. by a formal act: to grant a charter.
2. to give or accord: to grant permission.
3. to agree or accede to: to grant a request.
4. to admit or concede; accept for the sake of argument: I grant that point.
5. to transfer or convey, esp. by deed or writing: to grant property.
–noun 6. something granted, as a privilege or right, a sum of money, or a tract of land: Several major foundations made large grants to fund the research project.
7. the act of granting.
8. Law. a transfer of property.
9. a geographical unit in Vermont, Maine, and New Hampshire, originally a grant of land to a person or group of people.

"gratuitous bailment: a bailment in which there is no compensation or benefit to one party; especially : one that benefits only the bailor"
"Main Entry: bail·ment
Pronunciation: 'bAl-m&nt
Function: noun
Etymology: Anglo-French bayllment, from bailler to hand over —see BAIL
: the transfer of possession but not ownership of personal property (as goods) for a limited time or specified purpose (as transportation) such that the individual or business entity taking possession is liable to some extent for loss or damage to the property —compare DEPOSIT loan for consumption and loan for use at LOAN
NOTE: The typical elements of a bailment are delivery of the personal property, acceptance of the delivery, and possession or control of the property. Any of these elements may be actual or constructive. Bailments may be created by contracts, either express or implied, which require agreement, and the agreement may also be express or implied. Contracts for the lease of a car, for sale of goods on consignment, and for the transport of goods are examples of bailments."
http://dictionary.reference.com/search?db=mwlaw&q=bailment