Venetian internal trade routes and iron curtain, ftw. Settings are emperor, archipelago, standard, epic. The shot was taken long after I won ("one more turn"). You could probably squeeze in at least 200 more hammers with more land in the capital (desert hills would be best). 1K might be attainable. Disclaimer: obviously this isn't intended to be a strategy tip. Getting 600+ hammers this late in the game is strictly for the lulz.