This small complex of temples is situated around 20 km south from Battambang, and easily reachable by scooter or tuk-tuk by following street #1.
With his five-towers structure, it reminds a bit the site of Angkor Wat, but in a much smaller scale, so if you haven't been there yet it worth the shot.
Once you passed the main entrance, you will face a huge flight of steps that will bring you right up to the top of the 70-mt hill where the temples are. If you are worried about the heat, well, you shouldn't. A young khmer that will be happy to cool you with a fan, telling you something about the temple and hoping for a small tip. The steep steps up to the temple are worth the effort as there are stunning panoramic views from the top on the valley and on its endless paddies, as well as on the site of Phnom Sampeu.
About Wat Banan, we know that it was a Buddhist temple, but uncertain is the date of its built (somewhere around 10th and 13th century). The five corn-on-the-cob towers have well resisted to time, as well as the detailed stone lintels, whereas several of the carving have lost their heads to vandals (but a few are still in quite good conditions).