Event thumbnails on https://www.chrnox.com/start
Every file below is a public-domain or CC0 work obtained from Wikimedia Commons.
Verified programmatically against the Commons extmetadata API at fetch time.

agriculture	Maler_der_Grabkammer_des_Sennudem_001.jpg	Painter of the burial chamber of Sennedjem	Public domain	https://commons.wikimedia.org/wiki/File:Maler_der_Grabkammer_des_Sennudem_001.jpg
jericho	Tell_es-sultan.jpg	Fullo88 at Italian Wikipedia	Public domain	https://commons.wikimedia.org/wiki/File:Tell_es-sultan.jpg
writing	Sumerian_26th_c_Adab.jpg	Unknown author Unknown author	Public domain	https://commons.wikimedia.org/wiki/File:Sumerian_26th_c_Adab.jpg
bronze	Early_Bronze_Age_swords,_Central_Europe.jpg	Oscar Montellius	CC0	https://commons.wikimedia.org/wiki/File:Early_Bronze_Age_swords,_Central_Europe.jpg
pyramid	Description_de_l´Egypte_1.jpg	Anonymous Unknown author	Public domain	https://commons.wikimedia.org/wiki/File:Description_de_l%C2%B4Egypte_1.jpg
stonehenge	John Constable - Stonehenge - Google Art Project.jpg	John Constable	Public domain	https://commons.wikimedia.org/wiki/File:John_Constable_-_Stonehenge_-_Google_Art_Project.jpg
shang	Shang_Inscribed_Ox_Scapula_(for_divination).jpg	Unknown	CC0	https://commons.wikimedia.org/wiki/File:Shang_Inscribed_Ox_Scapula_(for_divination).jpg
iron	Nebra_disc_1.jpg	Frank Vincentz	Public domain	https://commons.wikimedia.org/wiki/File:Nebra_disc_1.jpg
romefound	Lupa_Capitolina,_Rome.jpg	Unknown	CC0	https://commons.wikimedia.org/wiki/File:Lupa_Capitolina,_Rome.jpg
athens	"The_School_of_Athens"_by_Raffaello_Sanzio_da_Urbino.jpg	Raphael	Public domain	https://commons.wikimedia.org/wiki/File:%22The_School_of_Athens%22_by_Raffaello_Sanzio_da_Urbino.jpg
han	漢武帝.jpg	Unknown author Unknown author	Public domain	https://commons.wikimedia.org/wiki/File:%E6%BC%A2%E6%AD%A6%E5%B8%9D.jpg
cleopatra	Kleopatra-VII.-Altes-Museum-Berlin1.jpg	Louis le Grand	Public domain	https://commons.wikimedia.org/wiki/File:Kleopatra-VII.-Altes-Museum-Berlin1.jpg
rome	Augustus Bevilacqua Glyptothek Munich 317.jpg	Unknown artist Unknown artist	Public domain	https://commons.wikimedia.org/wiki/File:Augustus_Bevilacqua_Glyptothek_Munich_317.jpg
maya	Dresden_Codex_pp.58-62_78.jpg	Unknown author Unknown author	Public domain	https://commons.wikimedia.org/wiki/File:Dresden_Codex_pp.58-62_78.jpg
byzantine	Eastern_Roman_Empire_565_CE.svg	Mnohohrishnyi	CC0	https://commons.wikimedia.org/wiki/File:Eastern_Roman_Empire_565_CE.svg
islamic	Al-Idrisi's_world_map.JPG	Unknown	Public domain	https://commons.wikimedia.org/wiki/File:Al-Idrisi%27s_world_map.JPG
magna	Magna_Carta_(British_Library_Cotton_MS_Augustus_II.106).jpg	Original authors were the barons and King John of England . Uploaded by Earthsound .	Public domain	https://commons.wikimedia.org/wiki/File:Magna_Carta_(British_Library_Cotton_MS_Augustus_II.106).jpg
plague	Pieter Bruegel the Elder - The Triumph of Death - WGA3389.jpg	Pieter Brueghel the Elder	Public domain	https://commons.wikimedia.org/wiki/File:Pieter_Bruegel_the_Elder_-_The_Triumph_of_Death_-_WGA3389.jpg
renaissance	Sandro Botticelli - La nascita di Venere - Google Art Project - edited.jpg	Sandro Botticelli	Public domain	https://commons.wikimedia.org/wiki/File:Sandro_Botticelli_-_La_nascita_di_Venere_-_Google_Art_Project_-_edited.jpg
printing	Printer in 1568-ce.png	Jost Amman	Public domain	https://commons.wikimedia.org/wiki/File:Printer_in_1568-ce.png
columbus	Portrait_of_a_Man,_Said_to_be_Christopher_Columbus.jpg	Sebastiano del Piombo	Public domain	https://commons.wikimedia.org/wiki/File:Portrait_of_a_Man,_Said_to_be_Christopher_Columbus.jpg
monalisa	Mona_Lisa,_by_Leonardo_da_Vinci,_from_C2RMF_natural_color.jpg	Leonardo da Vinci	Public domain	https://commons.wikimedia.org/wiki/File:Mona_Lisa,_by_Leonardo_da_Vinci,_from_C2RMF_natural_color.jpg
copernicus	Nikolaus_Kopernikus_MOT.jpg	Unknown author Unknown author	Public domain	https://commons.wikimedia.org/wiki/File:Nikolaus_Kopernikus_MOT.jpg
shakespeare	William_Shakespeare_by_John_Taylor,_edited.jpg	Attributed to John Taylor	Public domain	https://commons.wikimedia.org/wiki/File:William_Shakespeare_by_John_Taylor,_edited.jpg
galileo	Galileo_Galilei_(1564-1642)_RMG_BHC2700.tiff	Justus Sustermans	Public domain	https://commons.wikimedia.org/wiki/File:Galileo_Galilei_(1564-1642)_RMG_BHC2700.tiff
principia	Newton's_Principia_title_page.png	The original uploader was Zhaladshar at English Wikisource .	Public domain	https://commons.wikimedia.org/wiki/File:Newton%27s_Principia_title_page.png
enlightenment	Les_salons_au_XVIIIe_siècle_-_Histoire_Image.jpg	Anicet Charles Gabriel Lemonnier	Public domain	https://commons.wikimedia.org/wiki/File:Les_salons_au_XVIIIe_si%C3%A8cle_-_Histoire_Image.jpg
frenchrev	Anonymous_-_Prise_de_la_Bastille.jpg	Unidentified painter	Public domain	https://commons.wikimedia.org/wiki/File:Anonymous_-_Prise_de_la_Bastille.jpg
industrial	Powerloom_weaving_in_1835.jpg	Illustrator T. Allom, Engraver J. Tingle	Public domain	https://commons.wikimedia.org/wiki/File:Powerloom_weaving_in_1835.jpg
locomotive	Turner_-_Rain,_Steam_and_Speed_-_National_Gallery_file.jpg	J. M. W. Turner	Public domain	https://commons.wikimedia.org/wiki/File:Turner_-_Rain,_Steam_and_Speed_-_National_Gallery_file.jpg
wave	Tsunami_by_hokusai_19th_century.jpg	Katsushika Hokusai	Public domain	https://commons.wikimedia.org/wiki/File:Tsunami_by_hokusai_19th_century.jpg
austen	CassandraAusten-JaneAusten(c.1810)_hires.jpg	Cassandra Austen	Public domain	https://commons.wikimedia.org/wiki/File:CassandraAusten-JaneAusten(c.1810)_hires.jpg
darwin	Charles_Darwin_seated_crop.jpg	Charles_Darwin_seated.jpg : Henry Maull (1829–1914) and John Fox (1832–1907) (Maull & Fox) [ 3 ] derivative work: Bea o	Public domain	https://commons.wikimedia.org/wiki/File:Charles_Darwin_seated_crop.jpg
curie	Marie_Curie_c._1920s.jpg	Henri Manuel	Public domain	https://commons.wikimedia.org/wiki/File:Marie_Curie_c._1920s.jpg
flight	First_flight2.jpg	John T. Daniels	Public domain	https://commons.wikimedia.org/wiki/File:First_flight2.jpg
penicillin	Synthetic_Production_of_Penicillin_TR1468.jpg	Official photographer	Public domain	https://commons.wikimedia.org/wiki/File:Synthetic_Production_of_Penicillin_TR1468.jpg
dna	ADN animation.gif	brian0918 ™	Public domain	https://commons.wikimedia.org/wiki/File:DNA_animation.gif
earthrise	NASA-Apollo8-Dec24-Earthrise.jpg	NASA/Bill Anders	Public domain	https://commons.wikimedia.org/wiki/File:NASA-Apollo8-Dec24-Earthrise.jpg
apollo	Aldrin Apollo 11 original.jpg	Neil Armstrong	Public domain	https://commons.wikimedia.org/wiki/File:Aldrin_Apollo_11_original.jpg
web	WorldWideWeb.1.png	Ck_mpk	Public domain	https://commons.wikimedia.org/wiki/File:WorldWideWeb.1.png