The LACMA art museum has digitized a part of their collection and put it online—including 20,000 images for free download.

The Los Angeles County Museum of Art (LACMA) has been digitizing their collection for the past two years to make their art works viewable online.

By doing so, the institution has joined a row of the world leading museums in opening their collections to the public.

Today LACMA is the largest art museum in the western United States, with a collection of over 135,000 objects that illuminate 6,000 years of art history. Since its establishing in 1965, it has been devoted to collecting works of art that span both history and geography, from a broad range of cultures and historical periods, mirroring Los Angeles’s rich cultural heritage and uniquely diverse population. 

In total, the museum has uploaded 80,000 works on their website with both unrestricted and restricted use—which is more than a half of their physical collection. At the moment, there are 20,000 images available in the public domain for free download to anyone.
Хендрик Гольциус. Спящая Даная готовится к приему Юпитера
Спящая Даная готовится к приему Юпитера
Хендрик Гольциус
1603, 203.2×228.6×8.9 см

The website collection is enormous and it’s easy to find an art work that will inspire you.

The online search is sorted via highlights, objects on view, curatorial area, chronology, object type, and supplied by an advanced search. Each work is tagged with definite attributes for a convenient specific search. For instance, if you type "Athena", the website will bring up greek and roman statues, greek ceramics, etchings, and paintings from different eras.
Неизвестный  художник. Надежда Афина. Римская копия греческого оригинала 5 в. до н. э.
Надежда Афина. Римская копия греческого оригинала 5 в. до н. э.
Неизвестный художник
II век, 218.4×76.2×48.3 см

There are several different filters to narrow your search results. You can use all of them or only one. You can choose the option to see only results with images, or in public domain, or only on view.

LACMA provides all information available about an art work: name, author, date, material, style, size, collection, current place on view or in archives, curator notes, current and past exhibitions.
Рембрандт Харменс ван Рейн. Христос, исцеляющий больных
Христос, исцеляющий больных
Рембрандт Харменс ван Рейн
1649, 28.3×39.5 см

The collection amazes with the number of art works by renowned artists from different periods in art history, including Greek classics, Italian Renaissance, Dutch Baroque, Japanese Ukiyo-e, French Impressionism, Russian Abstractionism, Cubism and many more. Just look some works of what you'll find in the public domain.
Кацусика Хокусай. Южный Ветер, Ясный Рассвет
Южный Ветер, Ясный Рассвет
Кацусика Хокусай
25.4×36.5 см
Эдгар Дега. Арабеска
Эдгар Дега
3×3.9×1.4 см
Эдгар Дега. The Bellelli Sisters (Сёстры Джованна и Джулиана Беллелли)
The Bellelli Sisters (Сёстры Джованна и Джулиана Беллелли)
Эдгар Дега
92.1×72.4 см
Пьер Огюст Ренуар. Две девушки, читающие в саду
Две девушки, читающие в саду
Пьер Огюст Ренуар
1890, 80×73.7×10.2 см
Любовь Сергеевна Попова. Архитектоника Картины
Архитектоника Картины
Любовь Сергеевна Попова
1917, 83.8×61.6×5.1 см

LACMA collection includes all possible samples of visual arts, including painting, graphics, sculpture, decorative and applied arts. Just ramble through their website and find something special for you. Curator notes will help you learn interesting facts about an art work, its author, and period in the history of art it was made in. 

Written on materials of LACMA and