When released in PDF form the giant hardcover Ptolus: Monte Cook's City by the Spire was split into a series of 9 PDF files that made up the whole book. The first part is available free and does not have the series code PT1 listed on it even though it is referred to as Part 1 by the other section. PT2 to PT9 were released at initial prices varying between US$6 to US$12. Parts one to three were released before the full book, customers who had pre-ordered the book from the publisher were given access to download these PT2 and PT3 for free.
Note: Since the initial releases the whole combined book has been made available as a single PDF as well.
Each of these PDF files has a new covers not seen in the original book, the introduction from the original book and several chapters from the original book, and some additional notes on the change in formatting for the split version. In addition to having renumbered pages especially for the PDF, there was a second page number on each page referring to the original hardcover.
The nine PDF series that together is equivalent to the original book are (listed with release date, number of pages and initial pricing where known):
A Player's Guide to Ptolus (32 pages, FREE)
PT2: Ptolus: The World of Praemal (June 2006, 57 pages, $8)
PT3: Ptolus: Organizations (July 2006, 55 pages, $8)
PT4: Ptolus: Districts of the City, Vol. 1 (142 pages, $12)
PT5: Ptolus: Districts of the City, Vol. 2 (137 pages, $12)
PT6: Ptolus: DM's Companion (103 pages, $11)
PT7: Ptolus: Beneath the Streets (72 pages, $10)
PT8: Ptolus: Adventures (37 pages, $6)
PT9: Ptolus: The Spire (52 pages, $8)
From the introduction to each of the books:
This is one in a series of nine Ptolus PDF releases from Malhavoc Press. When used together, they comprise the entirety of the Ptolus print book. Each one is also usable on its own for city-based fantasy d20 roleplaying campaigns.