I'm seconding
>>1149863>>1149888By the same author as Thermae Romae, there are also Olympia Kyklos for lighter tone, and Plinivs for something more serious
Aoi Horus no Hitomi (Pharaoh Hatshepsut)
Sing! Erinna (SoL yonkoma, disciples of Sappho of Lesbos)
Heureka (Siege of Syracuse)
Alexandros
Waga na wa Nero
Jesus
Joan
Arte (Renaissance Italian Painters)
Cesare (Cesare Borgia)
Nobunaga no Chef (Time travel, modern to Sengoku Jidai)
Sengoku (Sengoku Jidai)
Reiri (Sengoku Jidai)
Hyouge Mono (Sengoku Jidai)
Vagabond (Manga version of Musashi novel)
Jin (Time travel, modern to late Edo period)
Yae no Sakura (Yamamoto Yaeko in the Boshin War)
Fushigi no Kuni no Bird (Isabella Bird travels in early Meiji Japan)
Ikoku Meiro no Croisee (SoL, Japanese girl in Belle Epoche Paris)
Otoyomegatari (Central Asian SoL romance during the Russian Conquest of Turkestan)
Victorian Romance Emma
Harukaze no Snegurochka (1920s Soviet Union)
Kuro Kishi Monogatari (WW2, Panzer crew in the Eastern Front)
The Cockpit (Anime anthology of 3: Ta-152 pilot, Kamikaze pilots, and Japanese soldiers in the Pacific)
War's Unwomanly Faces (manga version of the same nonfiction book. WW2 Soviet Union)
Onwards to Our Noble Deaths (semi-autobiography of the mangaka's experience as WW2 IJA soldier in Papua New Guinea)
Barefoot Gen (Hiroshima Bombing and the aftermath based on author's own experience)
Mitsurin Shounen (Khmer Rouge child soldier)
The author of Sing! Erinna just published her new Anna Komnena manga, but no scanlation yet.