Route 7 is another super short road that connects two cities; Celadon City and Saffron City. The building used to house an entrance to an Underground Path that led to Route 8, but it's been closed off because of unruly Trainers.
Catch some Dark Pokémon!
This small chunk of land leads to Template:~ (and contains another closed tunnel), but don't be concerned with that right now. What makes it noteworthy is the two Dark Pokémon that come out, naturally, at night. Half-Dark, half-Fire Houndour in particular evolves into one of the best Pokémon in the game. But even Murkrow is great for dealing with Sabrina's Psychic Gym.
Houndour is strong and versatile. Outside of Roar, all of the moves it learns are attacks, and they include Faint Attack (which never misses), Flamethrower, and Crunch, Dark's best attack. However, Houndour's evolved form, Houndoom (at level 24) has generally good stats (including impressive Speed), and its versatility makes it a good pick versus the game's tricky final opponent.
As Dark Pokémon go, Murkrow isn't that great. It has mediocre stats, a bad combination of types (there is already a plethora of Flying-types available), and really poor moves. Its most powerful attack is Faint Attack, the Dark version of Swift. Outside of that, you have Peck, Nightshade, and not much else. But it can learn Fly.
Rattata
Raticate
Meowth
Persian
Jigglypuff
Abra
Spearow
Growlithe
Vulpix
Snubbull
Murkrow
Houndour