Masaya [1] sits due south of the Managua–Granada Carretera along the east side of the Laguna de Masaya. The street that runs north along the plaza’s east side is the Calle Central, and as you travel it toward the Carretera, it becomes increasingly commercial.
One block east of the southeast corner of the park, you’ll find the stone walls of the Mercado Viejo [2] (Old Market). Walking six blocks west of the central park takes you to the hammock factories [3], baseball stadium, and malecón [4]; traveling due south leads you to Barrio Monimbó; going five blocks north puts you in the heart of the Barrio San Jerónimo around the church of the same name, situated at the famous siete esquinas (seven corners) intersection.
The heart of Masaya is easily walkable, but several hundred taxis, buses, horse-drawn carriages, and more exotic forms of transport will help you get out to the malecón or the highway.
Links:
[1] http://www.moon.com/destinations/nicaragua/masaya/masaya-city
[2] http://www.moon.com/destinations/nicaragua/masaya/masaya-city/sights/el-mercado-viejo-craft-market
[3] http://www.moon.com/destinations/nicaragua/masaya/masaya-city/sights/artisan-workshops
[4] http://www.moon.com/destinations/nicaragua/masaya/masaya-city/sights/el-malecon