The Leaky Cauldron - Though not really in Diagon Alley, it is the gateway between the Muggle world of London and the magical world of Harry Potter.  It is protected from being seen by normal persons and sits between a bookstore and a record shop.  The actual entrance to Diagon Alley is by tapping a brick in the back yard of the inn.  Rooms are available for rent.  I-67

Apothecary - I-72
    Silver Unicorn horns - 21 Galleons Each
    Beetle Eyes, Black - 5 Knuts a scoop
    Dragon's Liver - 17 Sickles an ounce
Cauldron's - I-72
Eeylops Owl Emporium - I-72
Florean Fortescues' Ice Cream Parlor - III-30
Flourish and Blots - Bookstore
Gambol and Japes Wizarding Joke Shop - II-58
Gladrags Wizardwear (London branch)
Gringott's Wizarding Bank - I-72
Junk Shop - II-38
Magical Managerie – III-
Madam Malkin's Robes for All Occasions I-76
Ollivander's – Fine wands since 382 B.C. I-81
Quality Quidditch Supplies - II-58 - I-72
Second Hand Robe Shop

Knockturn Alley - Shops devoted to the Dark Arts
Borgin and Burkes - II-53
poisonous candle shop - II-53