The Moonlit Market appears at the top of the Five Ways tower in Ankh-Morpork, usually after 10pm and before 5am when the full moon is in the sky. You'll need quite a bit of climbing skills, 200-250 bonus in rock and rope to get to the top.
The syntax to climb is: climb up, climb up, climb rope.
There another part an top of the tower that is part of the Radiant Adventurer quest where you climb onto the roof to get something from the telescope.
Also, you can 'jump out the window' instead of climbing back down the tower. This action has a check vs tumbling (ad.mo.tu) and 150 bonus seems to be enough. TPA shielding will take a hit as well. If you are wizard and jump out while FTF is active, you'll just float down to the ground.
If you are lacking in climbing bonuses, the climbing boots and climbing gloves from Slice can help boost your bonus.
Tom Grandison
Llenny Merridew
<colour> cravat (Notes: Sold by NPC for A$25) - syntax tie (for pe.am.cu TM)
Black leather boots (Notes: Sold by NPC for A$170)
Dark blue coat (Notes: Sold by NPC for A$15)
Dark grey cutaway jacket (Notes: Sold by NPC for A$117)
Deep green cutaway jacket (Notes: Sold by NPC for A$164.50)
Elegant black silk waistcoat (Notes: Sold by NPC for A$125)
Elegant grey silk waistcoat (Notes: Sold by NPC for A$140)
Elegant white silk waistcoat (Notes: Sold by NPC for A$12.50)
Fine cambric shirt (Notes: Sold by NPC for A$25)
Flowing black cloak (Notes: Sold by NPC for A$50)
Midnight black cutaway jacket (Notes: Sold by NPC for A$114.50)
Primrose yellow cutaway jacket (Notes: Sold by NPC for A$142)
Short ivory jacket (Notes: Sold by NPC for A$112.50)
Short midnight black jacket (Notes: Sold by NPC for A$112.50)
Short white jacket (Notes: Sold by NPC for A$112.50)
Star lined cloak (Notes: Sold by NPC for A$100)
Summer's night coat (Notes: Sold by NPC for A$140)
Tall black top hat (Notes: Sold by NPC for A$75)
Georgette Reyes
<colour/style> hipflask (Notes: Sold by NPC for A$50)
Assassins' metal box (Notes: Sold by NPC for A$17.50)
Black silk sash (Notes: Sold by NPC for A$40)
Blackened lockpick (Notes: Sold by NPC for A$21.25)
Blackened silver mirror (Notes: Sold by NPC for A$37.50)
Bordered initials embroidery pattern (Notes: Sold by NPC for A$2)
Delicate black towel (Notes: Sold by NPC for A$12.30)
Hertmes black crocodile handbag (Notes: Sold by NPC for A$450)
Hertmes grey ostrich handbag (Notes: Sold by NPC for A$325)
Hertmes raspberry pink lizard handbag (Notes: Sold by NPC for A$250)
Keyring necklace (Notes: Sold by NPC for A$4.45)
Tiny <colour> glass phial (Notes: Sold by NPC for A$2.50)
Utility belt (Notes: Sold by NPC for A$45)
Oscar Singleton - can also 'order' a tiger fang and pick it up the next Full Moon ($75)
<house animal> stiletto (Notes: Sold by NPC for A$75)
Blackened stiletto (Notes: Sold by NPC for A$75)
Dark red sword scabbard (Notes: Sold by NPC for A$2)
Dark-bladed poniard (Notes: Sold by NPC for A$132)
Elegant black fountain pen (Notes: Sold by NPC for A$100)
Steel tlinga (Notes: Sold by NPC for A$5.65)
Tiger fang (Notes: Sold by NPC for A$75)
Wicked little stiletto (Notes: Sold by NPC for A$75)
William Smith
Deep blue fountain pen (Notes: Sold by NPC for A$100)
Discworld map (Notes: Sold by NPC for A$15)
Elegant black fountain pen (Notes: Sold by NPC for A$100)
Exquisite vellum map (Notes: Sold by NPC for A$15)
Large Ramtops map (Notes: Sold by NPC for A$17.50)
Map of Djelibeybi (Notes: Sold by NPC for A$7.50)
Map of Klatch (Notes: Sold by NPC for A$7.50)
Midnight black quill pen (Notes: Sold by NPC for A$25)
Old Ramtops map (Notes: Sold by NPC for A$11.25)
Sheet of black widow parchment (Notes: Sold by NPC for A$1)
Sheet of cobra house parchment (Notes: Sold by NPC for A$1)
Sheet of scorpion parchment (Notes: Sold by NPC for A$1)
Sheet of tree frog parchment (Notes: Sold by NPC for A$1)
Sheet of viper house parchment (Notes: Sold by NPC for A$1)
Slim black fountain pen (Notes: Sold by NPC for A$100)
Item listings from Kefka's Item Database