When you have a winning formula, stick to it! That's the impetus that drove Hanna-Barbera to create this series in 1972. It's got all the elements of The Flintstones and The Jetsons with just a change of venue. Set in ancient Rome, this series follows the lives of the Holiday family, headed by hapless Gus (Dave Willock). Gus works in construction for the greedy Mr. Tycoonius (Hal Smith). The family lives with their pet lion Brutus (Daws Butler) in the Venus De Milo Arms apartment complex owned by their nemesis landlord, Mr. Evictus (DeLuise). Each week the family would get into typical sit-com situations. The show lasted for just one season, only 13 episodes were produced.
The series has yet to make it to DVD. It seems it was somewhat more popular in Brazil, where it was called Os Mussarelas (The Mozzarellas). You can find several episodes on YouTube and other sites dubbed into Portugese. Above are the opening credits in English, uploaded to YouTube by JediJuggernaut.
Obscurity factor: 10 (hard to find in English, not on DVD)