Synthesis of Pyrene from Benzene
Petroleum cracking and incomplete combusion of organic compounds may give pyrene in a complicated mixture as discussed in else where. However, if you looking at a method to prepare pure pyrene or its derivative you may need to go through [2.2]metacyclophane procedure (For review: Ref.1):

As seen in the above image, [2,2]metacyclophane can undergo transannular ring closure to yield products with the 4,5,9,10-tetrahydropyrene (THPy) skeleton (e.g., Ref.2), which may then be dehydrogenated to pyrene (Ref.3).
The synthesis of [2,2]metacyclophane(s) can be achieved from m-xylene. This can be in two steps: First, the bromination of two methyl group using NBS to achieve 1,2-bis(bromomethyl)benzene and then subjected the brominated m-xylene to Wurtz reaction (e.g., Ref.4). Recent approach of some substituted [2,2]metacyclophanes is described in Reference 5 starting with substituted m-xylenes (The electronic supplementary material is attached for readers benefit).
The synthesis of highly substituted pyrenes via cyclisation of bis-alkynylbiphenyls has been also achieved (e.g., Refs.6-8). It is worth noting that these starting biphenyls were made using simple benzene derivatives (Ref.1):


References:

Juan M. Casas-Solvas, Joshua D. Howgego, Anthony P. Davis, “Synthesis of substituted pyrenes by indirect methods,” Org. Biomol. Chem. 2014, 12, 212-232 (DOI: 10.1039/C3OB41993B)(PDF).
Fritz Vögtle, Peter Neumann, “Stereochemistry of [2.2]Metacyclophanes,” Angew. Chem., Int. Ed. Engl. 1972, 11(2), 73–83 (https://doi.org/10.1002/anie.197200731).
Peter P. Fu, Ronald G. Harvey, “Dehydrogenation of polycyclic hydroaromatic compounds,” Chem. Rev. 1978, 78(4), 317–361 (https://doi.org/10.1021/cr60314a001).
Virgil Boekelheide, Rodger W. Griffin Jr., “Synthesis of [2.2]metacyclophanes,” J. Org. Chem. 1969, 34(6), 1960–1961 (https://doi.org/10.1021/jo01258a095).
Marco Blangetti, Helge Müller-Bunza, Donal F. O'Shea, “First asymmetric synthesis of planar chiral [2.2]metacyclophanes,” Chem. Commun. 2013, 49(55), 6125-6127 (https://doi.org/10.1039/C3CC42275E)(Electronic Supplementary Material).
D. Barney Walker, Joshua Howgego, Anthony P. Davis, “Synthesis of Regioselectively Functionalized Pyrenes via Transition-Metal-Catalyzed Electrocyclization,” Synthesis 2010, (21), 3686-3692 (DOI: 10.1055/s-0030-1258238).
Matsuda Takanori, Moriya Taisaku, Goya Tsuyoshi, Murakami Masahiro, “Synthesis of Pyrenes by Twofold Hydroarylation of 2,6-Dialkynylbiphenyls,” Chemistry Letters 2011, 40(1), 40-41 (https://doi.org/10.1246/cl.2011.40).
Mareike M. Machuy, Christian Würtele, Peter R. Schreiner, “2,6-Bis(phenylethynyl)biphenyls and Their Cyclization to Pyrenes,” Synthesis 2012, 44(9), 1405-1409 (DOI: 10.1055/s-0031-1290754).