Technically, Ravana was Brahma's great-grandson.
Ravana's father was the famous rishi, Visravas, who himself was a son of Prajapati Pulastya, one of Brahma's ten 'mind-born' sons.
Ravana performed a yagya for Rama.
In one of the many versions of the Ramayana, it is said that once Rama's army had created the bridge to Lanka, they needed to get Shiva's blessing for which they set up a yagya. But the biggest bhakt of Shiva in the entire region was Ravana, and since he was half-brahman, he was also the best qualified to perform the yagya. Displaying honour, Ravan actually showed up, performed the yagya and gave Ram his blessing.
As he lay dying, Ravan imparted valuable knowledge to Lakshman.
Since Ravana was one of the most learned scholars to have ever lived, Rama asked his brother Lakshman to sit beside the dying demon-king and learn from him important lessons in statecraft and diplomacy.
Ravana was the maestro of Veena.
In many depictions of Ravan, he can be seen carrying a veena. It is believed that he had a keen interest in music and was a highly accomplished veena player.
Ravana had got Lanka as a gift when he did a prayer.
When Shiva called Ravana to do a puja, He was asked to take something in return. So he asked for Lanka which was originally made by Shiva for Parvati.
Ravan was well-aware of his impending doom.
Most powerful Asuras (demons) knew that they were sent to earth to perform a particular role. Ravana knew that it was his fate to die by the hands of an avatar of Vishnu, something that would help him attain moksha and give up his demon form. This was because he was one of Vishnu's doorkeepers who was cursed by a sage.
Sri Lakans think of Ravana as good.
Around 12.6% of Sri Lankans even worship Ravana. Sri Lankans worship Ravana for all that he is famed to do. For them, he was the king who resisted invaders. For them, he is the tragic hero who was betrayed by his own brothers when he tried to avenge his sister's honour. For them, he was the king who was blessed with the knowledge that his ten heads contained. For them, he was the king whose devotion to Lord Shiva won him powerful weapons.