If you want to apply for a visa to visit Belgium, you have to do so at the Belgium Visa application center. There is a Belgium Visa Application Center in Lagos and another one in Abuja.
The address of the Lagos visa application Centre is VFS Global,Manor House, Plot 110, Admiral Ayinla Way,Opposite Treasure Graden Estate, 3rd Roundabout, Lekki-Epe Expressway, Lekki Phase 1, Lagos while the Abuja Belgium Visa Application Center can be found at No. 38, Lobito Crescent, Wuse II, Abuja, Nigeria.
Belgium also has an Embassy in Nigeria which is located at 1A, Murtala Muhammed Drive, Former Bank Road, Ikoyi, Lagos. Postal address is P.O Box 149. Lagos while official phone numbers is 01-2691507.