Marib, about 60km away, was the ancient capital of the Sabaean kingdom and has its own extraordinary pre-Islamic monuments: the Great Marib Dam ruins, the Bar'an Temple (the Moon Temple), and the Awam Temple. Historically these two sites were combined in a single trip from Marib.
Sana'a, 125km away, has a UNESCO-listed old city of extraordinary medieval tower houses — one of the most distinctive urban landscapes in the Arab world.
Both sites are currently inaccessible due to Yemen's civil conflict.